/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "heap.h"
#define ATRACE_TAG ATRACE_TAG_DALVIK
#include <cutils/trace.h>
#include <limits>
#include <memory>
#include <vector>
#include "base/allocator.h"
#include "base/histogram-inl.h"
#include "base/stl_util.h"
#include "common_throws.h"
#include "cutils/sched_policy.h"
#include "debugger.h"
#include "gc/accounting/atomic_stack.h"
#include "gc/accounting/card_table-inl.h"
#include "gc/accounting/heap_bitmap-inl.h"
#include "gc/accounting/mod_union_table.h"
#include "gc/accounting/mod_union_table-inl.h"
#include "gc/accounting/remembered_set.h"
#include "gc/accounting/space_bitmap-inl.h"
#include "gc/collector/concurrent_copying.h"
#include "gc/collector/mark_compact.h"
#include "gc/collector/mark_sweep-inl.h"
#include "gc/collector/partial_mark_sweep.h"
#include "gc/collector/semi_space.h"
#include "gc/collector/sticky_mark_sweep.h"
#include "gc/reference_processor.h"
#include "gc/space/bump_pointer_space.h"
#include "gc/space/dlmalloc_space-inl.h"
#include "gc/space/image_space.h"
#include "gc/space/large_object_space.h"
#include "gc/space/rosalloc_space-inl.h"
#include "gc/space/space-inl.h"
#include "gc/space/zygote_space.h"
#include "entrypoints/quick/quick_alloc_entrypoints.h"
#include "heap-inl.h"
#include "image.h"
#include "intern_table.h"
#include "mirror/art_field-inl.h"
#include "mirror/class-inl.h"
#include "mirror/object.h"
#include "mirror/object-inl.h"
#include "mirror/object_array-inl.h"
#include "mirror/reference-inl.h"
#include "os.h"
#include "reflection.h"
#include "runtime.h"
#include "ScopedLocalRef.h"
#include "scoped_thread_state_change.h"
#include "handle_scope-inl.h"
#include "thread_list.h"
#include "well_known_classes.h"
namespace art {
namespace gc {
static constexpr size_t kCollectorTransitionStressIterations = 0;
static constexpr size_t kCollectorTransitionStressWait = 10 * 1000; // Microseconds
// Minimum amount of remaining bytes before a concurrent GC is triggered.
static constexpr size_t kMinConcurrentRemainingBytes = 128 * KB;
static constexpr size_t kMaxConcurrentRemainingBytes = 512 * KB;
// Sticky GC throughput adjustment, divided by 4. Increasing this causes sticky GC to occur more
// relative to partial/full GC. This may be desirable since sticky GCs interfere less with mutator
// threads (lower pauses, use less memory bandwidth).
static constexpr double kStickyGcThroughputAdjustment = 1.0;
// Whether or not we use the free list large object space. Only use it if USE_ART_LOW_4G_ALLOCATOR
// since this means that we have to use the slow msync loop in MemMap::MapAnonymous.
#if USE_ART_LOW_4G_ALLOCATOR
static constexpr bool kUseFreeListSpaceForLOS = true;
#else
static constexpr bool kUseFreeListSpaceForLOS = false;
#endif
// Whether or not we compact the zygote in PreZygoteFork.
static constexpr bool kCompactZygote = kMovingCollector;
// How many reserve entries are at the end of the allocation stack, these are only needed if the
// allocation stack overflows.
static constexpr size_t kAllocationStackReserveSize = 1024;
// Default mark stack size in bytes.
static const size_t kDefaultMarkStackSize = 64 * KB;
// Define space name.
static const char* kDlMallocSpaceName[2] = {"main dlmalloc space", "main dlmalloc space 1"};
static const char* kRosAllocSpaceName[2] = {"main rosalloc space", "main rosalloc space 1"};
static const char* kMemMapSpaceName[2] = {"main space", "main space 1"};
static const char* kNonMovingSpaceName = "non moving space";
static const char* kZygoteSpaceName = "zygote space";
static constexpr size_t kGSSBumpPointerSpaceCapacity = 32 * MB;
static constexpr bool kGCALotMode = false;
// GC alot mode uses a small allocation stack to stress test a lot of GC.
static constexpr size_t kGcAlotAllocationStackSize = 4 * KB /
sizeof(mirror::HeapReference<mirror::Object>);
// Verify objet has a small allocation stack size since searching the allocation stack is slow.
static constexpr size_t kVerifyObjectAllocationStackSize = 16 * KB /
sizeof(mirror::HeapReference<mirror::Object>);
static constexpr size_t kDefaultAllocationStackSize = 8 * MB /
sizeof(mirror::HeapReference<mirror::Object>);
Heap::Heap(size_t initial_size, size_t growth_limit, size_t min_free, size_t max_free,
double target_utilization, double foreground_heap_growth_multiplier,
size_t capacity, size_t non_moving_space_capacity, const std::string& image_file_name,
const InstructionSet image_instruction_set, CollectorType foreground_collector_type,
CollectorType background_collector_type, size_t parallel_gc_threads,
size_t conc_gc_threads, bool low_memory_mode,
size_t long_pause_log_threshold, size_t long_gc_log_threshold,
bool ignore_max_footprint, bool use_tlab,
bool verify_pre_gc_heap, bool verify_pre_sweeping_heap, bool verify_post_gc_heap,
bool verify_pre_gc_rosalloc, bool verify_pre_sweeping_rosalloc,
bool verify_post_gc_rosalloc, bool use_homogeneous_space_compaction_for_oom,
uint64_t min_interval_homogeneous_space_compaction_by_oom)
: non_moving_space_(nullptr),
rosalloc_space_(nullptr),
dlmalloc_space_(nullptr),
main_space_(nullptr),
collector_type_(kCollectorTypeNone),
foreground_collector_type_(foreground_collector_type),
background_collector_type_(background_collector_type),
desired_collector_type_(foreground_collector_type_),
heap_trim_request_lock_(nullptr),
last_trim_time_(0),
heap_transition_or_trim_target_time_(0),
heap_trim_request_pending_(false),
parallel_gc_threads_(parallel_gc_threads),
conc_gc_threads_(conc_gc_threads),
low_memory_mode_(low_memory_mode),
long_pause_log_threshold_(long_pause_log_threshold),
long_gc_log_threshold_(long_gc_log_threshold),
ignore_max_footprint_(ignore_max_footprint),
zygote_creation_lock_("zygote creation lock", kZygoteCreationLock),
have_zygote_space_(false),
large_object_threshold_(std::numeric_limits<size_t>::max()), // Starts out disabled.
collector_type_running_(kCollectorTypeNone),
last_gc_type_(collector::kGcTypeNone),
next_gc_type_(collector::kGcTypePartial),
capacity_(capacity),
growth_limit_(growth_limit),
max_allowed_footprint_(initial_size),
native_footprint_gc_watermark_(initial_size),
native_need_to_run_finalization_(false),
// Initially assume we perceive jank in case the process state is never updated.
process_state_(kProcessStateJankPerceptible),
concurrent_start_bytes_(std::numeric_limits<size_t>::max()),
total_bytes_freed_ever_(0),
total_objects_freed_ever_(0),
num_bytes_allocated_(0),
native_bytes_allocated_(0),
verify_missing_card_marks_(false),
verify_system_weaks_(false),
verify_pre_gc_heap_(verify_pre_gc_heap),
verify_pre_sweeping_heap_(verify_pre_sweeping_heap),
verify_post_gc_heap_(verify_post_gc_heap),
verify_mod_union_table_(false),
verify_pre_gc_rosalloc_(verify_pre_gc_rosalloc),
verify_pre_sweeping_rosalloc_(verify_pre_sweeping_rosalloc),
verify_post_gc_rosalloc_(verify_post_gc_rosalloc),
last_gc_time_ns_(NanoTime()),
allocation_rate_(0),
/* For GC a lot mode, we limit the allocations stacks to be kGcAlotInterval allocations. This
* causes a lot of GC since we do a GC for alloc whenever the stack is full. When heap
* verification is enabled, we limit the size of allocation stacks to speed up their
* searching.
*/
max_allocation_stack_size_(kGCALotMode ? kGcAlotAllocationStackSize
: (kVerifyObjectSupport > kVerifyObjectModeFast) ? kVerifyObjectAllocationStackSize :
kDefaultAllocationStackSize),
current_allocator_(kAllocatorTypeDlMalloc),
current_non_moving_allocator_(kAllocatorTypeNonMoving),
bump_pointer_space_(nullptr),
temp_space_(nullptr),
min_free_(min_free),
max_free_(max_free),
target_utilization_(target_utilization),
foreground_heap_growth_multiplier_(foreground_heap_growth_multiplier),
total_wait_time_(0),
total_allocation_time_(0),
verify_object_mode_(kVerifyObjectModeDisabled),
disable_moving_gc_count_(0),
running_on_valgrind_(Runtime::Current()->RunningOnValgrind()),
use_tlab_(use_tlab),
main_space_backup_(nullptr),
min_interval_homogeneous_space_compaction_by_oom_(
min_interval_homogeneous_space_compaction_by_oom),
last_time_homogeneous_space_compaction_by_oom_(NanoTime()),
use_homogeneous_space_compaction_for_oom_(use_homogeneous_space_compaction_for_oom) {
if (VLOG_IS_ON(heap) || VLOG_IS_ON(startup)) {
LOG(INFO) << "Heap() entering";
}
// If we aren't the zygote, switch to the default non zygote allocator. This may update the
// entrypoints.
const bool is_zygote = Runtime::Current()->IsZygote();
if (!is_zygote) {
large_object_threshold_ = kDefaultLargeObjectThreshold;
// Background compaction is currently not supported for command line runs.
if (background_collector_type_ != foreground_collector_type_) {
VLOG(heap) << "Disabling background compaction for non zygote";
background_collector_type_ = foreground_collector_type_;
}
}
ChangeCollector(desired_collector_type_);
live_bitmap_.reset(new accounting::HeapBitmap(this));
mark_bitmap_.reset(new accounting::HeapBitmap(this));
// Requested begin for the alloc space, to follow the mapped image and oat files
byte* requested_alloc_space_begin = nullptr;
if (!image_file_name.empty()) {
std::string error_msg;
space::ImageSpace* image_space = space::ImageSpace::Create(image_file_name.c_str(),
image_instruction_set,
&error_msg);
if (image_space != nullptr) {
AddSpace(image_space);
// Oat files referenced by image files immediately follow them in memory, ensure alloc space
// isn't going to get in the middle
byte* oat_file_end_addr = image_space->GetImageHeader().GetOatFileEnd();
CHECK_GT(oat_file_end_addr, image_space->End());
requested_alloc_space_begin = AlignUp(oat_file_end_addr, kPageSize);
} else {
LOG(WARNING) << "Could not create image space with image file '" << image_file_name << "'. "
<< "Attempting to fall back to imageless running. Error was: " << error_msg;
}
}
/*
requested_alloc_space_begin -> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
+- nonmoving space (non_moving_space_capacity)+-
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
+-????????????????????????????????????????????+-
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
+-main alloc space / bump space 1 (capacity_) +-
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
+-????????????????????????????????????????????+-
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
+-main alloc space2 / bump space 2 (capacity_)+-
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
*/
// We don't have hspace compaction enabled with GSS.
if (foreground_collector_type_ == kCollectorTypeGSS) {
use_homogeneous_space_compaction_for_oom_ = false;
}
bool support_homogeneous_space_compaction =
background_collector_type_ == gc::kCollectorTypeHomogeneousSpaceCompact ||
use_homogeneous_space_compaction_for_oom_;
// We may use the same space the main space for the non moving space if we don't need to compact
// from the main space.
// This is not the case if we support homogeneous compaction or have a moving background
// collector type.
bool separate_non_moving_space = is_zygote ||
support_homogeneous_space_compaction || IsMovingGc(foreground_collector_type_) ||
IsMovingGc(background_collector_type_);
if (foreground_collector_type == kCollectorTypeGSS) {
separate_non_moving_space = false;
}
std::unique_ptr<MemMap> main_mem_map_1;
std::unique_ptr<MemMap> main_mem_map_2;
byte* request_begin = requested_alloc_space_begin;
if (request_begin != nullptr && separate_non_moving_space) {
request_begin += non_moving_space_capacity;
}
std::string error_str;
std::unique_ptr<MemMap> non_moving_space_mem_map;
if (separate_non_moving_space) {
// If we are the zygote, the non moving space becomes the zygote space when we run
// PreZygoteFork the first time. In this case, call the map "zygote space" since we can't
// rename the mem map later.
const char* space_name = is_zygote ? kZygoteSpaceName: kNonMovingSpaceName;
// Reserve the non moving mem map before the other two since it needs to be at a specific
// address.
non_moving_space_mem_map.reset(
MemMap::MapAnonymous(space_name, requested_alloc_space_begin,
non_moving_space_capacity, PROT_READ | PROT_WRITE, true, &error_str));
CHECK(non_moving_space_mem_map != nullptr) << error_str;
// Try to reserve virtual memory at a lower address if we have a separate non moving space.
request_begin = reinterpret_cast<byte*>(300 * MB);
}
// Attempt to create 2 mem maps at or after the requested begin.
main_mem_map_1.reset(MapAnonymousPreferredAddress(kMemMapSpaceName[0], request_begin, capacity_,
PROT_READ | PROT_WRITE, &error_str));
CHECK(main_mem_map_1.get() != nullptr) << error_str;
if (support_homogeneous_space_compaction ||
background_collector_type_ == kCollectorTypeSS ||
foreground_collector_type_ == kCollectorTypeSS) {
main_mem_map_2.reset(MapAnonymousPreferredAddress(kMemMapSpaceName[1], main_mem_map_1->End(),
capacity_, PROT_READ | PROT_WRITE,
&error_str));
CHECK(main_mem_map_2.get() != nullptr) << error_str;
}
// Create the non moving space first so that bitmaps don't take up the address range.
if (separate_non_moving_space) {
// Non moving space is always dlmalloc since we currently don't have support for multiple
// active rosalloc spaces.
const size_t size = non_moving_space_mem_map->Size();
non_moving_space_ = space::DlMallocSpace::CreateFromMemMap(
non_moving_space_mem_map.release(), "zygote / non moving space", kDefaultStartingSize,
initial_size, size, size, false);
non_moving_space_->SetFootprintLimit(non_moving_space_->Capacity());
CHECK(non_moving_space_ != nullptr) << "Failed creating non moving space "
<< requested_alloc_space_begin;
AddSpace(non_moving_space_);
}
// Create other spaces based on whether or not we have a moving GC.
if (IsMovingGc(foreground_collector_type_) && foreground_collector_type_ != kCollectorTypeGSS) {
// Create bump pointer spaces.
// We only to create the bump pointer if the foreground collector is a compacting GC.
// TODO: Place bump-pointer spaces somewhere to minimize size of card table.
bump_pointer_space_ = space::BumpPointerSpace::CreateFromMemMap("Bump pointer space 1",
main_mem_map_1.release());
CHECK(bump_pointer_space_ != nullptr) << "Failed to create bump pointer space";
AddSpace(bump_pointer_space_);
temp_space_ = space::BumpPointerSpace::CreateFromMemMap("Bump pointer space 2",
main_mem_map_2.release());
CHECK(temp_space_ != nullptr) << "Failed to create bump pointer space";
AddSpace(temp_space_);
CHECK(separate_non_moving_space);
} else {
CreateMainMallocSpace(main_mem_map_1.release(), initial_size, growth_limit_, capacity_);
CHECK(main_space_ != nullptr);
AddSpace(main_space_);
if (!separate_non_moving_space) {
non_moving_space_ = main_space_;
CHECK(!non_moving_space_->CanMoveObjects());
}
if (foreground_collector_type_ == kCollectorTypeGSS) {
CHECK_EQ(foreground_collector_type_, background_collector_type_);
// Create bump pointer spaces instead of a backup space.
main_mem_map_2.release();
bump_pointer_space_ = space::BumpPointerSpace::Create("Bump pointer space 1",
kGSSBumpPointerSpaceCapacity, nullptr);
CHECK(bump_pointer_space_ != nullptr);
AddSpace(bump_pointer_space_);
temp_space_ = space::BumpPointerSpace::Create("Bump pointer space 2",
kGSSBumpPointerSpaceCapacity, nullptr);
CHECK(temp_space_ != nullptr);
AddSpace(temp_space_);
} else if (main_mem_map_2.get() != nullptr) {
const char* name = kUseRosAlloc ? kRosAllocSpaceName[1] : kDlMallocSpaceName[1];
main_space_backup_.reset(CreateMallocSpaceFromMemMap(main_mem_map_2.release(), initial_size,
growth_limit_, capacity_, name, true));
CHECK(main_space_backup_.get() != nullptr);
// Add the space so its accounted for in the heap_begin and heap_end.
AddSpace(main_space_backup_.get());
}
}
CHECK(non_moving_space_ != nullptr);
CHECK(!non_moving_space_->CanMoveObjects());
// Allocate the large object space.
if (kUseFreeListSpaceForLOS) {
large_object_space_ = space::FreeListSpace::Create("large object space", nullptr, capacity_);
} else {
large_object_space_ = space::LargeObjectMapSpace::Create("large object space");
}
CHECK(large_object_space_ != nullptr) << "Failed to create large object space";
AddSpace(large_object_space_);
// Compute heap capacity. Continuous spaces are sorted in order of Begin().
CHECK(!continuous_spaces_.empty());
// Relies on the spaces being sorted.
byte* heap_begin = continuous_spaces_.front()->Begin();
byte* heap_end = continuous_spaces_.back()->Limit();
size_t heap_capacity = heap_end - heap_begin;
// Remove the main backup space since it slows down the GC to have unused extra spaces.
// TODO: Avoid needing to do this.
if (main_space_backup_.get() != nullptr) {
RemoveSpace(main_space_backup_.get());
}
// Allocate the card table.
card_table_.reset(accounting::CardTable::Create(heap_begin, heap_capacity));
CHECK(card_table_.get() != NULL) << "Failed to create card table";
// Card cache for now since it makes it easier for us to update the references to the copying
// spaces.
accounting::ModUnionTable* mod_union_table =
new accounting::ModUnionTableToZygoteAllocspace("Image mod-union table", this,
GetImageSpace());
CHECK(mod_union_table != nullptr) << "Failed to create image mod-union table";
AddModUnionTable(mod_union_table);
if (collector::SemiSpace::kUseRememberedSet && non_moving_space_ != main_space_) {
accounting::RememberedSet* non_moving_space_rem_set =
new accounting::RememberedSet("Non-moving space remembered set", this, non_moving_space_);
CHECK(non_moving_space_rem_set != nullptr) << "Failed to create non-moving space remembered set";
AddRememberedSet(non_moving_space_rem_set);
}
// TODO: Count objects in the image space here?
num_bytes_allocated_.StoreRelaxed(0);
mark_stack_.reset(accounting::ObjectStack::Create("mark stack", kDefaultMarkStackSize,
kDefaultMarkStackSize));
const size_t alloc_stack_capacity = max_allocation_stack_size_ + kAllocationStackReserveSize;
allocation_stack_.reset(accounting::ObjectStack::Create(
"allocation stack", max_allocation_stack_size_, alloc_stack_capacity));
live_stack_.reset(accounting::ObjectStack::Create(
"live stack", max_allocation_stack_size_, alloc_stack_capacity));
// It's still too early to take a lock because there are no threads yet, but we can create locks
// now. We don't create it earlier to make it clear that you can't use locks during heap
// initialization.
gc_complete_lock_ = new Mutex("GC complete lock");
gc_complete_cond_.reset(new ConditionVariable("GC complete condition variable",
*gc_complete_lock_));
heap_trim_request_lock_ = new Mutex("Heap trim request lock");
last_gc_size_ = GetBytesAllocated();
if (ignore_max_footprint_) {
SetIdealFootprint(std::numeric_limits<size_t>::max());
concurrent_start_bytes_ = std::numeric_limits<size_t>::max();
}
CHECK_NE(max_allowed_footprint_, 0U);
// Create our garbage collectors.
for (size_t i = 0; i < 2; ++i) {
const bool concurrent = i != 0;
garbage_collectors_.push_back(new collector::MarkSweep(this, concurrent));
garbage_collectors_.push_back(new collector::PartialMarkSweep(this, concurrent));
garbage_collectors_.push_back(new collector::StickyMarkSweep(this, concurrent));
}
if (kMovingCollector) {
// TODO: Clean this up.
const bool generational = foreground_collector_type_ == kCollectorTypeGSS;
semi_space_collector_ = new collector::SemiSpace(this, generational,
generational ? "generational" : "");
garbage_collectors_.push_back(semi_space_collector_);
concurrent_copying_collector_ = new collector::ConcurrentCopying(this);
garbage_collectors_.push_back(concurrent_copying_collector_);
mark_compact_collector_ = new collector::MarkCompact(this);
garbage_collectors_.push_back(mark_compact_collector_);
}
if (GetImageSpace() != nullptr && non_moving_space_ != nullptr) {
// Check that there's no gap between the image space and the non moving space so that the
// immune region won't break (eg. due to a large object allocated in the gap).
bool no_gap = MemMap::CheckNoGaps(GetImageSpace()->GetMemMap(),
non_moving_space_->GetMemMap());
if (!no_gap) {
MemMap::DumpMaps(LOG(ERROR));
LOG(FATAL) << "There's a gap between the image space and the main space";
}
}
if (running_on_valgrind_) {
Runtime::Current()->GetInstrumentation()->InstrumentQuickAllocEntryPoints();
}
if (VLOG_IS_ON(heap) || VLOG_IS_ON(startup)) {
LOG(INFO) << "Heap() exiting";
}
}
MemMap* Heap::MapAnonymousPreferredAddress(const char* name, byte* request_begin, size_t capacity,
int prot_flags, std::string* out_error_str) {
while (true) {
MemMap* map = MemMap::MapAnonymous(kMemMapSpaceName[0], request_begin, capacity,
PROT_READ | PROT_WRITE, true, out_error_str);
if (map != nullptr || request_begin == nullptr) {
return map;
}
// Retry a second time with no specified request begin.
request_begin = nullptr;
}
return nullptr;
}
space::MallocSpace* Heap::CreateMallocSpaceFromMemMap(MemMap* mem_map, size_t initial_size,
size_t growth_limit, size_t capacity,
const char* name, bool can_move_objects) {
space::MallocSpace* malloc_space = nullptr;
if (kUseRosAlloc) {
// Create rosalloc space.
malloc_space = space::RosAllocSpace::CreateFromMemMap(mem_map, name, kDefaultStartingSize,
initial_size, growth_limit, capacity,
low_memory_mode_, can_move_objects);
} else {
malloc_space = space::DlMallocSpace::CreateFromMemMap(mem_map, name, kDefaultStartingSize,
initial_size, growth_limit, capacity,
can_move_objects);
}
if (collector::SemiSpace::kUseRememberedSet) {
accounting::RememberedSet* rem_set =
new accounting::RememberedSet(std::string(name) + " remembered set", this, malloc_space);
CHECK(rem_set != nullptr) << "Failed to create main space remembered set";
AddRememberedSet(rem_set);
}
CHECK(malloc_space != nullptr) << "Failed to create " << name;
malloc_space->SetFootprintLimit(malloc_space->Capacity());
return malloc_space;
}
void Heap::CreateMainMallocSpace(MemMap* mem_map, size_t initial_size, size_t growth_limit,
size_t capacity) {
// Is background compaction is enabled?
bool can_move_objects = IsMovingGc(background_collector_type_) !=
IsMovingGc(foreground_collector_type_) || use_homogeneous_space_compaction_for_oom_;
// If we are the zygote and don't yet have a zygote space, it means that the zygote fork will
// happen in the future. If this happens and we have kCompactZygote enabled we wish to compact
// from the main space to the zygote space. If background compaction is enabled, always pass in
// that we can move objets.
if (kCompactZygote && Runtime::Current()->IsZygote() && !can_move_objects) {
// After the zygote we want this to be false if we don't have background compaction enabled so
// that getting primitive array elements is faster.
// We never have homogeneous compaction with GSS and don't need a space with movable objects.
can_move_objects = !have_zygote_space_ && foreground_collector_type_ != kCollectorTypeGSS;
}
if (collector::SemiSpace::kUseRememberedSet && main_space_ != nullptr) {
RemoveRememberedSet(main_space_);
}
const char* name = kUseRosAlloc ? kRosAllocSpaceName[0] : kDlMallocSpaceName[0];
main_space_ = CreateMallocSpaceFromMemMap(mem_map, initial_size, growth_limit, capacity, name,
can_move_objects);
SetSpaceAsDefault(main_space_);
VLOG(heap) << "Created main space " << main_space_;
}
void Heap::ChangeAllocator(AllocatorType allocator) {
if (current_allocator_ != allocator) {
// These two allocators are only used internally and don't have any entrypoints.
CHECK_NE(allocator, kAllocatorTypeLOS);
CHECK_NE(allocator, kAllocatorTypeNonMoving);
current_allocator_ = allocator;
MutexLock mu(nullptr, *Locks::runtime_shutdown_lock_);
SetQuickAllocEntryPointsAllocator(current_allocator_);
Runtime::Current()->GetInstrumentation()->ResetQuickAllocEntryPoints();
}
}
void Heap::DisableMovingGc() {
if (IsMovingGc(foreground_collector_type_)) {
foreground_collector_type_ = kCollectorTypeCMS;
}
if (IsMovingGc(background_collector_type_)) {
background_collector_type_ = foreground_collector_type_;
}
TransitionCollector(foreground_collector_type_);
ThreadList* tl = Runtime::Current()->GetThreadList();
Thread* self = Thread::Current();
ScopedThreadStateChange tsc(self, kSuspended);
tl->SuspendAll();
// Something may have caused the transition to fail.
if (!IsMovingGc(collector_type_) && non_moving_space_ != main_space_) {
CHECK(main_space_ != nullptr);
// The allocation stack may have non movable objects in it. We need to flush it since the GC
// can't only handle marking allocation stack objects of one non moving space and one main
// space.
{
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
FlushAllocStack();
}
main_space_->DisableMovingObjects();
non_moving_space_ = main_space_;
CHECK(!non_moving_space_->CanMoveObjects());
}
tl->ResumeAll();
}
std::string Heap::SafeGetClassDescriptor(mirror::Class* klass) {
if (!IsValidContinuousSpaceObjectAddress(klass)) {
return StringPrintf("<non heap address klass %p>", klass);
}
mirror::Class* component_type = klass->GetComponentType<kVerifyNone>();
if (IsValidContinuousSpaceObjectAddress(component_type) && klass->IsArrayClass<kVerifyNone>()) {
std::string result("[");
result += SafeGetClassDescriptor(component_type);
return result;
} else if (UNLIKELY(klass->IsPrimitive<kVerifyNone>())) {
return Primitive::Descriptor(klass->GetPrimitiveType<kVerifyNone>());
} else if (UNLIKELY(klass->IsProxyClass<kVerifyNone>())) {
return Runtime::Current()->GetClassLinker()->GetDescriptorForProxy(klass);
} else {
mirror::DexCache* dex_cache = klass->GetDexCache<kVerifyNone>();
if (!IsValidContinuousSpaceObjectAddress(dex_cache)) {
return StringPrintf("<non heap address dex_cache %p>", dex_cache);
}
const DexFile* dex_file = dex_cache->GetDexFile();
uint16_t class_def_idx = klass->GetDexClassDefIndex();
if (class_def_idx == DexFile::kDexNoIndex16) {
return "<class def not found>";
}
const DexFile::ClassDef& class_def = dex_file->GetClassDef(class_def_idx);
const DexFile::TypeId& type_id = dex_file->GetTypeId(class_def.class_idx_);
return dex_file->GetTypeDescriptor(type_id);
}
}
std::string Heap::SafePrettyTypeOf(mirror::Object* obj) {
if (obj == nullptr) {
return "null";
}
mirror::Class* klass = obj->GetClass<kVerifyNone>();
if (klass == nullptr) {
return "(class=null)";
}
std::string result(SafeGetClassDescriptor(klass));
if (obj->IsClass()) {
result += "<" + SafeGetClassDescriptor(obj->AsClass<kVerifyNone>()) + ">";
}
return result;
}
void Heap::DumpObject(std::ostream& stream, mirror::Object* obj) {
if (obj == nullptr) {
stream << "(obj=null)";
return;
}
if (IsAligned<kObjectAlignment>(obj)) {
space::Space* space = nullptr;
// Don't use find space since it only finds spaces which actually contain objects instead of
// spaces which may contain objects (e.g. cleared bump pointer spaces).
for (const auto& cur_space : continuous_spaces_) {
if (cur_space->HasAddress(obj)) {
space = cur_space;
break;
}
}
// Unprotect all the spaces.
for (const auto& space : continuous_spaces_) {
mprotect(space->Begin(), space->Capacity(), PROT_READ | PROT_WRITE);
}
stream << "Object " << obj;
if (space != nullptr) {
stream << " in space " << *space;
}
mirror::Class* klass = obj->GetClass<kVerifyNone>();
stream << "\nclass=" << klass;
if (klass != nullptr) {
stream << " type= " << SafePrettyTypeOf(obj);
}
// Re-protect the address we faulted on.
mprotect(AlignDown(obj, kPageSize), kPageSize, PROT_NONE);
}
}
bool Heap::IsCompilingBoot() const {
if (!Runtime::Current()->IsCompiler()) {
return false;
}
for (const auto& space : continuous_spaces_) {
if (space->IsImageSpace() || space->IsZygoteSpace()) {
return false;
}
}
return true;
}
bool Heap::HasImageSpace() const {
for (const auto& space : continuous_spaces_) {
if (space->IsImageSpace()) {
return true;
}
}
return false;
}
void Heap::IncrementDisableMovingGC(Thread* self) {
// Need to do this holding the lock to prevent races where the GC is about to run / running when
// we attempt to disable it.
ScopedThreadStateChange tsc(self, kWaitingForGcToComplete);
MutexLock mu(self, *gc_complete_lock_);
++disable_moving_gc_count_;
if (IsMovingGc(collector_type_running_)) {
WaitForGcToCompleteLocked(kGcCauseDisableMovingGc, self);
}
}
void Heap::DecrementDisableMovingGC(Thread* self) {
MutexLock mu(self, *gc_complete_lock_);
CHECK_GE(disable_moving_gc_count_, 0U);
--disable_moving_gc_count_;
}
void Heap::UpdateProcessState(ProcessState process_state) {
if (process_state_ != process_state) {
process_state_ = process_state;
for (size_t i = 1; i <= kCollectorTransitionStressIterations; ++i) {
// Start at index 1 to avoid "is always false" warning.
// Have iteration 1 always transition the collector.
TransitionCollector((((i & 1) == 1) == (process_state_ == kProcessStateJankPerceptible))
? foreground_collector_type_ : background_collector_type_);
usleep(kCollectorTransitionStressWait);
}
if (process_state_ == kProcessStateJankPerceptible) {
// Transition back to foreground right away to prevent jank.
RequestCollectorTransition(foreground_collector_type_, 0);
} else {
// Don't delay for debug builds since we may want to stress test the GC.
// If background_collector_type_ is kCollectorTypeHomogeneousSpaceCompact then we have
// special handling which does a homogenous space compaction once but then doesn't transition
// the collector.
RequestCollectorTransition(background_collector_type_,
kIsDebugBuild ? 0 : kCollectorTransitionWait);
}
}
}
void Heap::CreateThreadPool() {
const size_t num_threads = std::max(parallel_gc_threads_, conc_gc_threads_);
if (num_threads != 0) {
thread_pool_.reset(new ThreadPool("Heap thread pool", num_threads));
}
}
void Heap::VisitObjects(ObjectCallback callback, void* arg) {
Thread* self = Thread::Current();
// GCs can move objects, so don't allow this.
const char* old_cause = self->StartAssertNoThreadSuspension("Visiting objects");
if (bump_pointer_space_ != nullptr) {
// Visit objects in bump pointer space.
bump_pointer_space_->Walk(callback, arg);
}
// TODO: Switch to standard begin and end to use ranged a based loop.
for (mirror::Object** it = allocation_stack_->Begin(), **end = allocation_stack_->End();
it < end; ++it) {
mirror::Object* obj = *it;
if (obj != nullptr && obj->GetClass() != nullptr) {
// Avoid the race condition caused by the object not yet being written into the allocation
// stack or the class not yet being written in the object. Or, if kUseThreadLocalAllocationStack,
// there can be nulls on the allocation stack.
callback(obj, arg);
}
}
GetLiveBitmap()->Walk(callback, arg);
self->EndAssertNoThreadSuspension(old_cause);
}
void Heap::MarkAllocStackAsLive(accounting::ObjectStack* stack) {
space::ContinuousSpace* space1 = main_space_ != nullptr ? main_space_ : non_moving_space_;
space::ContinuousSpace* space2 = non_moving_space_;
// TODO: Generalize this to n bitmaps?
CHECK(space1 != nullptr);
CHECK(space2 != nullptr);
MarkAllocStack(space1->GetLiveBitmap(), space2->GetLiveBitmap(),
large_object_space_->GetLiveBitmap(), stack);
}
void Heap::DeleteThreadPool() {
thread_pool_.reset(nullptr);
}
void Heap::AddSpace(space::Space* space) {
CHECK(space != nullptr);
WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
if (space->IsContinuousSpace()) {
DCHECK(!space->IsDiscontinuousSpace());
space::ContinuousSpace* continuous_space = space->AsContinuousSpace();
// Continuous spaces don't necessarily have bitmaps.
accounting::ContinuousSpaceBitmap* live_bitmap = continuous_space->GetLiveBitmap();
accounting::ContinuousSpaceBitmap* mark_bitmap = continuous_space->GetMarkBitmap();
if (live_bitmap != nullptr) {
CHECK(mark_bitmap != nullptr);
live_bitmap_->AddContinuousSpaceBitmap(live_bitmap);
mark_bitmap_->AddContinuousSpaceBitmap(mark_bitmap);
}
continuous_spaces_.push_back(continuous_space);
// Ensure that spaces remain sorted in increasing order of start address.
std::sort(continuous_spaces_.begin(), continuous_spaces_.end(),
[](const space::ContinuousSpace* a, const space::ContinuousSpace* b) {
return a->Begin() < b->Begin();
});
} else {
CHECK(space->IsDiscontinuousSpace());
space::DiscontinuousSpace* discontinuous_space = space->AsDiscontinuousSpace();
live_bitmap_->AddLargeObjectBitmap(discontinuous_space->GetLiveBitmap());
mark_bitmap_->AddLargeObjectBitmap(discontinuous_space->GetMarkBitmap());
discontinuous_spaces_.push_back(discontinuous_space);
}
if (space->IsAllocSpace()) {
alloc_spaces_.push_back(space->AsAllocSpace());
}
}
void Heap::SetSpaceAsDefault(space::ContinuousSpace* continuous_space) {
WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
if (continuous_space->IsDlMallocSpace()) {
dlmalloc_space_ = continuous_space->AsDlMallocSpace();
} else if (continuous_space->IsRosAllocSpace()) {
rosalloc_space_ = continuous_space->AsRosAllocSpace();
}
}
void Heap::RemoveSpace(space::Space* space) {
DCHECK(space != nullptr);
WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
if (space->IsContinuousSpace()) {
DCHECK(!space->IsDiscontinuousSpace());
space::ContinuousSpace* continuous_space = space->AsContinuousSpace();
// Continuous spaces don't necessarily have bitmaps.
accounting::ContinuousSpaceBitmap* live_bitmap = continuous_space->GetLiveBitmap();
accounting::ContinuousSpaceBitmap* mark_bitmap = continuous_space->GetMarkBitmap();
if (live_bitmap != nullptr) {
DCHECK(mark_bitmap != nullptr);
live_bitmap_->RemoveContinuousSpaceBitmap(live_bitmap);
mark_bitmap_->RemoveContinuousSpaceBitmap(mark_bitmap);
}
auto it = std::find(continuous_spaces_.begin(), continuous_spaces_.end(), continuous_space);
DCHECK(it != continuous_spaces_.end());
continuous_spaces_.erase(it);
} else {
DCHECK(space->IsDiscontinuousSpace());
space::DiscontinuousSpace* discontinuous_space = space->AsDiscontinuousSpace();
live_bitmap_->RemoveLargeObjectBitmap(discontinuous_space->GetLiveBitmap());
mark_bitmap_->RemoveLargeObjectBitmap(discontinuous_space->GetMarkBitmap());
auto it = std::find(discontinuous_spaces_.begin(), discontinuous_spaces_.end(),
discontinuous_space);
DCHECK(it != discontinuous_spaces_.end());
discontinuous_spaces_.erase(it);
}
if (space->IsAllocSpace()) {
auto it = std::find(alloc_spaces_.begin(), alloc_spaces_.end(), space->AsAllocSpace());
DCHECK(it != alloc_spaces_.end());
alloc_spaces_.erase(it);
}
}
void Heap::DumpGcPerformanceInfo(std::ostream& os) {
// Dump cumulative timings.
os << "Dumping cumulative Gc timings\n";
uint64_t total_duration = 0;
// Dump cumulative loggers for each GC type.
uint64_t total_paused_time = 0;
for (auto& collector : garbage_collectors_) {
const CumulativeLogger& logger = collector->GetCumulativeTimings();
const size_t iterations = logger.GetIterations();
const Histogram<uint64_t>& pause_histogram = collector->GetPauseHistogram();
if (iterations != 0 && pause_histogram.SampleSize() != 0) {
os << ConstDumpable<CumulativeLogger>(logger);
const uint64_t total_ns = logger.GetTotalNs();
const uint64_t total_pause_ns = collector->GetTotalPausedTimeNs();
double seconds = NsToMs(logger.GetTotalNs()) / 1000.0;
const uint64_t freed_bytes = collector->GetTotalFreedBytes();
const uint64_t freed_objects = collector->GetTotalFreedObjects();
Histogram<uint64_t>::CumulativeData cumulative_data;
pause_histogram.CreateHistogram(&cumulative_data);
pause_histogram.PrintConfidenceIntervals(os, 0.99, cumulative_data);
os << collector->GetName() << " total time: " << PrettyDuration(total_ns)
<< " mean time: " << PrettyDuration(total_ns / iterations) << "\n"
<< collector->GetName() << " freed: " << freed_objects
<< " objects with total size " << PrettySize(freed_bytes) << "\n"
<< collector->GetName() << " throughput: " << freed_objects / seconds << "/s / "
<< PrettySize(freed_bytes / seconds) << "/s\n";
total_duration += total_ns;
total_paused_time += total_pause_ns;
}
collector->ResetMeasurements();
}
uint64_t allocation_time =
static_cast<uint64_t>(total_allocation_time_.LoadRelaxed()) * kTimeAdjust;
if (total_duration != 0) {
const double total_seconds = static_cast<double>(total_duration / 1000) / 1000000.0;
os << "Total time spent in GC: " << PrettyDuration(total_duration) << "\n";
os << "Mean GC size throughput: "
<< PrettySize(GetBytesFreedEver() / total_seconds) << "/s\n";
os << "Mean GC object throughput: "
<< (GetObjectsFreedEver() / total_seconds) << " objects/s\n";
}
uint64_t total_objects_allocated = GetObjectsAllocatedEver();
os << "Total number of allocations " << total_objects_allocated << "\n";
uint64_t total_bytes_allocated = GetBytesAllocatedEver();
os << "Total bytes allocated " << PrettySize(total_bytes_allocated) << "\n";
os << "Free memory " << PrettySize(GetFreeMemory()) << "\n";
os << "Free memory until GC " << PrettySize(GetFreeMemoryUntilGC()) << "\n";
os << "Free memory until OOME " << PrettySize(GetFreeMemoryUntilOOME()) << "\n";
os << "Total memory " << PrettySize(GetTotalMemory()) << "\n";
os << "Max memory " << PrettySize(GetMaxMemory()) << "\n";
if (kMeasureAllocationTime) {
os << "Total time spent allocating: " << PrettyDuration(allocation_time) << "\n";
os << "Mean allocation time: " << PrettyDuration(allocation_time / total_objects_allocated)
<< "\n";
}
os << "Total mutator paused time: " << PrettyDuration(total_paused_time) << "\n";
os << "Total time waiting for GC to complete: " << PrettyDuration(total_wait_time_) << "\n";
BaseMutex::DumpAll(os);
}
Heap::~Heap() {
VLOG(heap) << "Starting ~Heap()";
STLDeleteElements(&garbage_collectors_);
// If we don't reset then the mark stack complains in its destructor.
allocation_stack_->Reset();
live_stack_->Reset();
STLDeleteValues(&mod_union_tables_);
STLDeleteValues(&remembered_sets_);
STLDeleteElements(&continuous_spaces_);
STLDeleteElements(&discontinuous_spaces_);
delete gc_complete_lock_;
delete heap_trim_request_lock_;
VLOG(heap) << "Finished ~Heap()";
}
space::ContinuousSpace* Heap::FindContinuousSpaceFromObject(const mirror::Object* obj,
bool fail_ok) const {
for (const auto& space : continuous_spaces_) {
if (space->Contains(obj)) {
return space;
}
}
if (!fail_ok) {
LOG(FATAL) << "object " << reinterpret_cast<const void*>(obj) << " not inside any spaces!";
}
return NULL;
}
space::DiscontinuousSpace* Heap::FindDiscontinuousSpaceFromObject(const mirror::Object* obj,
bool fail_ok) const {
for (const auto& space : discontinuous_spaces_) {
if (space->Contains(obj)) {
return space;
}
}
if (!fail_ok) {
LOG(FATAL) << "object " << reinterpret_cast<const void*>(obj) << " not inside any spaces!";
}
return NULL;
}
space::Space* Heap::FindSpaceFromObject(const mirror::Object* obj, bool fail_ok) const {
space::Space* result = FindContinuousSpaceFromObject(obj, true);
if (result != NULL) {
return result;
}
return FindDiscontinuousSpaceFromObject(obj, true);
}
space::ImageSpace* Heap::GetImageSpace() const {
for (const auto& space : continuous_spaces_) {
if (space->IsImageSpace()) {
return space->AsImageSpace();
}
}
return NULL;
}
void Heap::ThrowOutOfMemoryError(Thread* self, size_t byte_count, AllocatorType allocator_type) {
std::ostringstream oss;
size_t total_bytes_free = GetFreeMemory();
oss << "Failed to allocate a " << byte_count << " byte allocation with " << total_bytes_free
<< " free bytes and " << PrettySize(GetFreeMemoryUntilOOME()) << " until OOM";
// If the allocation failed due to fragmentation, print out the largest continuous allocation.
if (total_bytes_free >= byte_count) {
space::AllocSpace* space = nullptr;
if (allocator_type == kAllocatorTypeNonMoving) {
space = non_moving_space_;
} else if (allocator_type == kAllocatorTypeRosAlloc ||
allocator_type == kAllocatorTypeDlMalloc) {
space = main_space_;
} else if (allocator_type == kAllocatorTypeBumpPointer ||
allocator_type == kAllocatorTypeTLAB) {
space = bump_pointer_space_;
}
if (space != nullptr) {
space->LogFragmentationAllocFailure(oss, byte_count);
}
}
self->ThrowOutOfMemoryError(oss.str().c_str());
}
void Heap::DoPendingTransitionOrTrim() {
Thread* self = Thread::Current();
CollectorType desired_collector_type;
// Wait until we reach the desired transition time.
while (true) {
uint64_t wait_time;
{
MutexLock mu(self, *heap_trim_request_lock_);
desired_collector_type = desired_collector_type_;
uint64_t current_time = NanoTime();
if (current_time >= heap_transition_or_trim_target_time_) {
break;
}
wait_time = heap_transition_or_trim_target_time_ - current_time;
}
ScopedThreadStateChange tsc(self, kSleeping);
usleep(wait_time / 1000); // Usleep takes microseconds.
}
// Launch homogeneous space compaction if it is desired.
if (desired_collector_type == kCollectorTypeHomogeneousSpaceCompact) {
if (!CareAboutPauseTimes()) {
PerformHomogeneousSpaceCompact();
}
// No need to Trim(). Homogeneous space compaction may free more virtual and physical memory.
desired_collector_type = collector_type_;
return;
}
// Transition the collector if the desired collector type is not the same as the current
// collector type.
TransitionCollector(desired_collector_type);
if (!CareAboutPauseTimes()) {
// Deflate the monitors, this can cause a pause but shouldn't matter since we don't care
// about pauses.
Runtime* runtime = Runtime::Current();
runtime->GetThreadList()->SuspendAll();
uint64_t start_time = NanoTime();
size_t count = runtime->GetMonitorList()->DeflateMonitors();
VLOG(heap) << "Deflating " << count << " monitors took "
<< PrettyDuration(NanoTime() - start_time);
runtime->GetThreadList()->ResumeAll();
}
// Do a heap trim if it is needed.
Trim();
}
class TrimIndirectReferenceTableClosure : public Closure {
public:
explicit TrimIndirectReferenceTableClosure(Barrier* barrier) : barrier_(barrier) {
}
virtual void Run(Thread* thread) OVERRIDE NO_THREAD_SAFETY_ANALYSIS {
ATRACE_BEGIN("Trimming reference table");
thread->GetJniEnv()->locals.Trim();
ATRACE_END();
barrier_->Pass(Thread::Current());
}
private:
Barrier* const barrier_;
};
void Heap::Trim() {
Thread* self = Thread::Current();
{
MutexLock mu(self, *heap_trim_request_lock_);
if (!heap_trim_request_pending_ || last_trim_time_ + kHeapTrimWait >= NanoTime()) {
return;
}
last_trim_time_ = NanoTime();
heap_trim_request_pending_ = false;
}
{
// Need to do this before acquiring the locks since we don't want to get suspended while
// holding any locks.
ScopedThreadStateChange tsc(self, kWaitingForGcToComplete);
// Pretend we are doing a GC to prevent background compaction from deleting the space we are
// trimming.
MutexLock mu(self, *gc_complete_lock_);
// Ensure there is only one GC at a time.
WaitForGcToCompleteLocked(kGcCauseTrim, self);
collector_type_running_ = kCollectorTypeHeapTrim;
}
// Trim reference tables.
{
ScopedObjectAccess soa(self);
JavaVMExt* vm = soa.Vm();
// Trim globals indirect reference table.
{
WriterMutexLock mu(self, vm->globals_lock);
vm->globals.Trim();
}
// Trim locals indirect reference tables.
Barrier barrier(0);
TrimIndirectReferenceTableClosure closure(&barrier);
ScopedThreadStateChange tsc(self, kWaitingForCheckPointsToRun);
size_t barrier_count = Runtime::Current()->GetThreadList()->RunCheckpoint(&closure);
barrier.Increment(self, barrier_count);
}
uint64_t start_ns = NanoTime();
// Trim the managed spaces.
uint64_t total_alloc_space_allocated = 0;
uint64_t total_alloc_space_size = 0;
uint64_t managed_reclaimed = 0;
for (const auto& space : continuous_spaces_) {
if (space->IsMallocSpace()) {
gc::space::MallocSpace* malloc_space = space->AsMallocSpace();
if (malloc_space->IsRosAllocSpace() || !CareAboutPauseTimes()) {
// Don't trim dlmalloc spaces if we care about pauses since this can hold the space lock
// for a long period of time.
managed_reclaimed += malloc_space->Trim();
}
total_alloc_space_size += malloc_space->Size();
}
}
total_alloc_space_allocated = GetBytesAllocated() - large_object_space_->GetBytesAllocated();
if (bump_pointer_space_ != nullptr) {
total_alloc_space_allocated -= bump_pointer_space_->Size();
}
const float managed_utilization = static_cast<float>(total_alloc_space_allocated) /
static_cast<float>(total_alloc_space_size);
uint64_t gc_heap_end_ns = NanoTime();
// We never move things in the native heap, so we can finish the GC at this point.
FinishGC(self, collector::kGcTypeNone);
size_t native_reclaimed = 0;
// Only trim the native heap if we don't care about pauses.
if (!CareAboutPauseTimes()) {
#if defined(USE_DLMALLOC)
// Trim the native heap.
dlmalloc_trim(0);
dlmalloc_inspect_all(DlmallocMadviseCallback, &native_reclaimed);
#elif defined(USE_JEMALLOC)
// Jemalloc does it's own internal trimming.
#else
UNIMPLEMENTED(WARNING) << "Add trimming support";
#endif
}
uint64_t end_ns = NanoTime();
VLOG(heap) << "Heap trim of managed (duration=" << PrettyDuration(gc_heap_end_ns - start_ns)
<< ", advised=" << PrettySize(managed_reclaimed) << ") and native (duration="
<< PrettyDuration(end_ns - gc_heap_end_ns) << ", advised=" << PrettySize(native_reclaimed)
<< ") heaps. Managed heap utilization of " << static_cast<int>(100 * managed_utilization)
<< "%.";
}
bool Heap::IsValidObjectAddress(const mirror::Object* obj) const {
// Note: we deliberately don't take the lock here, and mustn't test anything that would require
// taking the lock.
if (obj == nullptr) {
return true;
}
return IsAligned<kObjectAlignment>(obj) && FindSpaceFromObject(obj, true) != nullptr;
}
bool Heap::IsNonDiscontinuousSpaceHeapAddress(const mirror::Object* obj) const {
return FindContinuousSpaceFromObject(obj, true) != nullptr;
}
bool Heap::IsValidContinuousSpaceObjectAddress(const mirror::Object* obj) const {
if (obj == nullptr || !IsAligned<kObjectAlignment>(obj)) {
return false;
}
for (const auto& space : continuous_spaces_) {
if (space->HasAddress(obj)) {
return true;
}
}
return false;
}
bool Heap::IsLiveObjectLocked(mirror::Object* obj, bool search_allocation_stack,
bool search_live_stack, bool sorted) {
if (UNLIKELY(!IsAligned<kObjectAlignment>(obj))) {
return false;
}
if (bump_pointer_space_ != nullptr && bump_pointer_space_->HasAddress(obj)) {
mirror::Class* klass = obj->GetClass<kVerifyNone>();
if (obj == klass) {
// This case happens for java.lang.Class.
return true;
}
return VerifyClassClass(klass) && IsLiveObjectLocked(klass);
} else if (temp_space_ != nullptr && temp_space_->HasAddress(obj)) {
// If we are in the allocated region of the temp space, then we are probably live (e.g. during
// a GC). When a GC isn't running End() - Begin() is 0 which means no objects are contained.
return temp_space_->Contains(obj);
}
space::ContinuousSpace* c_space = FindContinuousSpaceFromObject(obj, true);
space::DiscontinuousSpace* d_space = nullptr;
if (c_space != nullptr) {
if (c_space->GetLiveBitmap()->Test(obj)) {
return true;
}
} else {
d_space = FindDiscontinuousSpaceFromObject(obj, true);
if (d_space != nullptr) {
if (d_space->GetLiveBitmap()->Test(obj)) {
return true;
}
}
}
// This is covering the allocation/live stack swapping that is done without mutators suspended.
for (size_t i = 0; i < (sorted ? 1 : 5); ++i) {
if (i > 0) {
NanoSleep(MsToNs(10));
}
if (search_allocation_stack) {
if (sorted) {
if (allocation_stack_->ContainsSorted(obj)) {
return true;
}
} else if (allocation_stack_->Contains(obj)) {
return true;
}
}
if (search_live_stack) {
if (sorted) {
if (live_stack_->ContainsSorted(obj)) {
return true;
}
} else if (live_stack_->Contains(obj)) {
return true;
}
}
}
// We need to check the bitmaps again since there is a race where we mark something as live and
// then clear the stack containing it.
if (c_space != nullptr) {
if (c_space->GetLiveBitmap()->Test(obj)) {
return true;
}
} else {
d_space = FindDiscontinuousSpaceFromObject(obj, true);
if (d_space != nullptr && d_space->GetLiveBitmap()->Test(obj)) {
return true;
}
}
return false;
}
std::string Heap::DumpSpaces() const {
std::ostringstream oss;
DumpSpaces(oss);
return oss.str();
}
void Heap::DumpSpaces(std::ostream& stream) const {
for (const auto& space : continuous_spaces_) {
accounting::ContinuousSpaceBitmap* live_bitmap = space->GetLiveBitmap();
accounting::ContinuousSpaceBitmap* mark_bitmap = space->GetMarkBitmap();
stream << space << " " << *space << "\n";
if (live_bitmap != nullptr) {
stream << live_bitmap << " " << *live_bitmap << "\n";
}
if (mark_bitmap != nullptr) {
stream << mark_bitmap << " " << *mark_bitmap << "\n";
}
}
for (const auto& space : discontinuous_spaces_) {
stream << space << " " << *space << "\n";
}
}
void Heap::VerifyObjectBody(mirror::Object* obj) {
if (verify_object_mode_ == kVerifyObjectModeDisabled) {
return;
}
// Ignore early dawn of the universe verifications.
if (UNLIKELY(static_cast<size_t>(num_bytes_allocated_.LoadRelaxed()) < 10 * KB)) {
return;
}
CHECK(IsAligned<kObjectAlignment>(obj)) << "Object isn't aligned: " << obj;
mirror::Class* c = obj->GetFieldObject<mirror::Class, kVerifyNone>(mirror::Object::ClassOffset());
CHECK(c != nullptr) << "Null class in object " << obj;
CHECK(IsAligned<kObjectAlignment>(c)) << "Class " << c << " not aligned in object " << obj;
CHECK(VerifyClassClass(c));
if (verify_object_mode_ > kVerifyObjectModeFast) {
// Note: the bitmap tests below are racy since we don't hold the heap bitmap lock.
CHECK(IsLiveObjectLocked(obj)) << "Object is dead " << obj << "\n" << DumpSpaces();
}
}
void Heap::VerificationCallback(mirror::Object* obj, void* arg) {
reinterpret_cast<Heap*>(arg)->VerifyObjectBody(obj);
}
void Heap::VerifyHeap() {
ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
GetLiveBitmap()->Walk(Heap::VerificationCallback, this);
}
void Heap::RecordFree(uint64_t freed_objects, int64_t freed_bytes) {
// Use signed comparison since freed bytes can be negative when background compaction foreground
// transitions occurs. This is caused by the moving objects from a bump pointer space to a
// free list backed space typically increasing memory footprint due to padding and binning.
DCHECK_LE(freed_bytes, static_cast<int64_t>(num_bytes_allocated_.LoadRelaxed()));
// Note: This relies on 2s complement for handling negative freed_bytes.
num_bytes_allocated_.FetchAndSubSequentiallyConsistent(static_cast<ssize_t>(freed_bytes));
if (Runtime::Current()->HasStatsEnabled()) {
RuntimeStats* thread_stats = Thread::Current()->GetStats();
thread_stats->freed_objects += freed_objects;
thread_stats->freed_bytes += freed_bytes;
// TODO: Do this concurrently.
RuntimeStats* global_stats = Runtime::Current()->GetStats();
global_stats->freed_objects += freed_objects;
global_stats->freed_bytes += freed_bytes;
}
}
space::RosAllocSpace* Heap::GetRosAllocSpace(gc::allocator::RosAlloc* rosalloc) const {
for (const auto& space : continuous_spaces_) {
if (space->AsContinuousSpace()->IsRosAllocSpace()) {
if (space->AsContinuousSpace()->AsRosAllocSpace()->GetRosAlloc() == rosalloc) {
return space->AsContinuousSpace()->AsRosAllocSpace();
}
}
}
return nullptr;
}
mirror::Object* Heap::AllocateInternalWithGc(Thread* self, AllocatorType allocator,
size_t alloc_size, size_t* bytes_allocated,
size_t* usable_size,
mirror::Class** klass) {
bool was_default_allocator = allocator == GetCurrentAllocator();
// Make sure there is no pending exception since we may need to throw an OOME.
self->AssertNoPendingException();
DCHECK(klass != nullptr);
StackHandleScope<1> hs(self);
HandleWrapper<mirror::Class> h(hs.NewHandleWrapper(klass));
klass = nullptr; // Invalidate for safety.
// The allocation failed. If the GC is running, block until it completes, and then retry the
// allocation.
collector::GcType last_gc = WaitForGcToComplete(kGcCauseForAlloc, self);
if (last_gc != collector::kGcTypeNone) {
// If we were the default allocator but the allocator changed while we were suspended,
// abort the allocation.
if (was_default_allocator && allocator != GetCurrentAllocator()) {
return nullptr;
}
// A GC was in progress and we blocked, retry allocation now that memory has been freed.
mirror::Object* ptr = TryToAllocate<true, false>(self, allocator, alloc_size, bytes_allocated,
usable_size);
if (ptr != nullptr) {
return ptr;
}
}
collector::GcType tried_type = next_gc_type_;
const bool gc_ran =
CollectGarbageInternal(tried_type, kGcCauseForAlloc, false) != collector::kGcTypeNone;
if (was_default_allocator && allocator != GetCurrentAllocator()) {
return nullptr;
}
if (gc_ran) {
mirror::Object* ptr = TryToAllocate<true, false>(self, allocator, alloc_size, bytes_allocated,
usable_size);
if (ptr != nullptr) {
return ptr;
}
}
// Loop through our different Gc types and try to Gc until we get enough free memory.
for (collector::GcType gc_type : gc_plan_) {
if (gc_type == tried_type) {
continue;
}
// Attempt to run the collector, if we succeed, re-try the allocation.
const bool gc_ran =
CollectGarbageInternal(gc_type, kGcCauseForAlloc, false) != collector::kGcTypeNone;
if (was_default_allocator && allocator != GetCurrentAllocator()) {
return nullptr;
}
if (gc_ran) {
// Did we free sufficient memory for the allocation to succeed?
mirror::Object* ptr = TryToAllocate<true, false>(self, allocator, alloc_size, bytes_allocated,
usable_size);
if (ptr != nullptr) {
return ptr;
}
}
}
// Allocations have failed after GCs; this is an exceptional state.
// Try harder, growing the heap if necessary.
mirror::Object* ptr = TryToAllocate<true, true>(self, allocator, alloc_size, bytes_allocated,
usable_size);
if (ptr != nullptr) {
return ptr;
}
// Most allocations should have succeeded by now, so the heap is really full, really fragmented,
// or the requested size is really big. Do another GC, collecting SoftReferences this time. The
// VM spec requires that all SoftReferences have been collected and cleared before throwing
// OOME.
VLOG(gc) << "Forcing collection of SoftReferences for " << PrettySize(alloc_size)
<< " allocation";
// TODO: Run finalization, but this may cause more allocations to occur.
// We don't need a WaitForGcToComplete here either.
DCHECK(!gc_plan_.empty());
CollectGarbageInternal(gc_plan_.back(), kGcCauseForAlloc, true);
if (was_default_allocator && allocator != GetCurrentAllocator()) {
return nullptr;
}
ptr = TryToAllocate<true, true>(self, allocator, alloc_size, bytes_allocated, usable_size);
if (ptr == nullptr) {
const uint64_t current_time = NanoTime();
switch (allocator) {
case kAllocatorTypeRosAlloc:
// Fall-through.
case kAllocatorTypeDlMalloc: {
if (use_homogeneous_space_compaction_for_oom_ &&
current_time - last_time_homogeneous_space_compaction_by_oom_ >
min_interval_homogeneous_space_compaction_by_oom_) {
last_time_homogeneous_space_compaction_by_oom_ = current_time;
HomogeneousSpaceCompactResult result = PerformHomogeneousSpaceCompact();
switch (result) {
case HomogeneousSpaceCompactResult::kSuccess:
// If the allocation succeeded, we delayed an oom.
ptr = TryToAllocate<true, true>(self, allocator, alloc_size, bytes_allocated,
usable_size);
if (ptr != nullptr) {
count_delayed_oom_++;
}
break;
case HomogeneousSpaceCompactResult::kErrorReject:
// Reject due to disabled moving GC.
break;
case HomogeneousSpaceCompactResult::kErrorVMShuttingDown:
// Throw OOM by default.
break;
default: {
LOG(FATAL) << "Unimplemented homogeneous space compaction result "
<< static_cast<size_t>(result);
}
}
// Always print that we ran homogeneous space compation since this can cause jank.
VLOG(heap) << "Ran heap homogeneous space compaction, "
<< " requested defragmentation "
<< count_requested_homogeneous_space_compaction_.LoadSequentiallyConsistent()
<< " performed defragmentation "
<< count_performed_homogeneous_space_compaction_.LoadSequentiallyConsistent()
<< " ignored homogeneous space compaction "
<< count_ignored_homogeneous_space_compaction_.LoadSequentiallyConsistent()
<< " delayed count = "
<< count_delayed_oom_.LoadSequentiallyConsistent();
}
break;
}
case kAllocatorTypeNonMoving: {
// Try to transition the heap if the allocation failure was due to the space being full.
if (!IsOutOfMemoryOnAllocation<false>(allocator, alloc_size)) {
// If we aren't out of memory then the OOM was probably from the non moving space being
// full. Attempt to disable compaction and turn the main space into a non moving space.
DisableMovingGc();
// If we are still a moving GC then something must have caused the transition to fail.
if (IsMovingGc(collector_type_)) {
MutexLock mu(self, *gc_complete_lock_);
// If we couldn't disable moving GC, just throw OOME and return null.
LOG(WARNING) << "Couldn't disable moving GC with disable GC count "
<< disable_moving_gc_count_;
} else {
LOG(WARNING) << "Disabled moving GC due to the non moving space being full";
ptr = TryToAllocate<true, true>(self, allocator, alloc_size, bytes_allocated,
usable_size);
}
}
break;
}
default: {
// Do nothing for others allocators.
}
}
}
// If the allocation hasn't succeeded by this point, throw an OOM error.
if (ptr == nullptr) {
ThrowOutOfMemoryError(self, alloc_size, allocator);
}
return ptr;
}
void Heap::SetTargetHeapUtilization(float target) {
DCHECK_GT(target, 0.0f); // asserted in Java code
DCHECK_LT(target, 1.0f);
target_utilization_ = target;
}
size_t Heap::GetObjectsAllocated() const {
size_t total = 0;
for (space::AllocSpace* space : alloc_spaces_) {
total += space->GetObjectsAllocated();
}
return total;
}
uint64_t Heap::GetObjectsAllocatedEver() const {
return GetObjectsFreedEver() + GetObjectsAllocated();
}
uint64_t Heap::GetBytesAllocatedEver() const {
return GetBytesFreedEver() + GetBytesAllocated();
}
class InstanceCounter {
public:
InstanceCounter(const std::vector<mirror::Class*>& classes, bool use_is_assignable_from, uint64_t* counts)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: classes_(classes), use_is_assignable_from_(use_is_assignable_from), counts_(counts) {
}
static void Callback(mirror::Object* obj, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
InstanceCounter* instance_counter = reinterpret_cast<InstanceCounter*>(arg);
mirror::Class* instance_class = obj->GetClass();
CHECK(instance_class != nullptr);
for (size_t i = 0; i < instance_counter->classes_.size(); ++i) {
if (instance_counter->use_is_assignable_from_) {
if (instance_counter->classes_[i]->IsAssignableFrom(instance_class)) {
++instance_counter->counts_[i];
}
} else if (instance_class == instance_counter->classes_[i]) {
++instance_counter->counts_[i];
}
}
}
private:
const std::vector<mirror::Class*>& classes_;
bool use_is_assignable_from_;
uint64_t* const counts_;
DISALLOW_COPY_AND_ASSIGN(InstanceCounter);
};
void Heap::CountInstances(const std::vector<mirror::Class*>& classes, bool use_is_assignable_from,
uint64_t* counts) {
// Can't do any GC in this function since this may move classes.
Thread* self = Thread::Current();
auto* old_cause = self->StartAssertNoThreadSuspension("CountInstances");
InstanceCounter counter(classes, use_is_assignable_from, counts);
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
VisitObjects(InstanceCounter::Callback, &counter);
self->EndAssertNoThreadSuspension(old_cause);
}
class InstanceCollector {
public:
InstanceCollector(mirror::Class* c, int32_t max_count, std::vector<mirror::Object*>& instances)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: class_(c), max_count_(max_count), instances_(instances) {
}
static void Callback(mirror::Object* obj, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
DCHECK(arg != nullptr);
InstanceCollector* instance_collector = reinterpret_cast<InstanceCollector*>(arg);
mirror::Class* instance_class = obj->GetClass();
if (instance_class == instance_collector->class_) {
if (instance_collector->max_count_ == 0 ||
instance_collector->instances_.size() < instance_collector->max_count_) {
instance_collector->instances_.push_back(obj);
}
}
}
private:
mirror::Class* class_;
uint32_t max_count_;
std::vector<mirror::Object*>& instances_;
DISALLOW_COPY_AND_ASSIGN(InstanceCollector);
};
void Heap::GetInstances(mirror::Class* c, int32_t max_count,
std::vector<mirror::Object*>& instances) {
// Can't do any GC in this function since this may move classes.
Thread* self = Thread::Current();
auto* old_cause = self->StartAssertNoThreadSuspension("GetInstances");
InstanceCollector collector(c, max_count, instances);
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
VisitObjects(&InstanceCollector::Callback, &collector);
self->EndAssertNoThreadSuspension(old_cause);
}
class ReferringObjectsFinder {
public:
ReferringObjectsFinder(mirror::Object* object, int32_t max_count,
std::vector<mirror::Object*>& referring_objects)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_)
: object_(object), max_count_(max_count), referring_objects_(referring_objects) {
}
static void Callback(mirror::Object* obj, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
reinterpret_cast<ReferringObjectsFinder*>(arg)->operator()(obj);
}
// For bitmap Visit.
// TODO: Fix lock analysis to not use NO_THREAD_SAFETY_ANALYSIS, requires support for
// annotalysis on visitors.
void operator()(mirror::Object* o) const NO_THREAD_SAFETY_ANALYSIS {
o->VisitReferences<true>(*this, VoidFunctor());
}
// For Object::VisitReferences.
void operator()(mirror::Object* obj, MemberOffset offset, bool /* is_static */) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
mirror::Object* ref = obj->GetFieldObject<mirror::Object>(offset);
if (ref == object_ && (max_count_ == 0 || referring_objects_.size() < max_count_)) {
referring_objects_.push_back(obj);
}
}
private:
mirror::Object* object_;
uint32_t max_count_;
std::vector<mirror::Object*>& referring_objects_;
DISALLOW_COPY_AND_ASSIGN(ReferringObjectsFinder);
};
void Heap::GetReferringObjects(mirror::Object* o, int32_t max_count,
std::vector<mirror::Object*>& referring_objects) {
// Can't do any GC in this function since this may move the object o.
Thread* self = Thread::Current();
auto* old_cause = self->StartAssertNoThreadSuspension("GetReferringObjects");
ReferringObjectsFinder finder(o, max_count, referring_objects);
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
VisitObjects(&ReferringObjectsFinder::Callback, &finder);
self->EndAssertNoThreadSuspension(old_cause);
}
void Heap::CollectGarbage(bool clear_soft_references) {
// Even if we waited for a GC we still need to do another GC since weaks allocated during the
// last GC will not have necessarily been cleared.
CollectGarbageInternal(gc_plan_.back(), kGcCauseExplicit, clear_soft_references);
}
HomogeneousSpaceCompactResult Heap::PerformHomogeneousSpaceCompact() {
Thread* self = Thread::Current();
// Inc requested homogeneous space compaction.
count_requested_homogeneous_space_compaction_++;
// Store performed homogeneous space compaction at a new request arrival.
ThreadList* tl = Runtime::Current()->GetThreadList();
ScopedThreadStateChange tsc(self, kWaitingPerformingGc);
Locks::mutator_lock_->AssertNotHeld(self);
{
ScopedThreadStateChange tsc(self, kWaitingForGcToComplete);
MutexLock mu(self, *gc_complete_lock_);
// Ensure there is only one GC at a time.
WaitForGcToCompleteLocked(kGcCauseHomogeneousSpaceCompact, self);
// Homogeneous space compaction is a copying transition, can't run it if the moving GC disable count
// is non zero.
// If the collector type changed to something which doesn't benefit from homogeneous space compaction,
// exit.
if (disable_moving_gc_count_ != 0 || IsMovingGc(collector_type_) ||
!main_space_->CanMoveObjects()) {
return HomogeneousSpaceCompactResult::kErrorReject;
}
collector_type_running_ = kCollectorTypeHomogeneousSpaceCompact;
}
if (Runtime::Current()->IsShuttingDown(self)) {
// Don't allow heap transitions to happen if the runtime is shutting down since these can
// cause objects to get finalized.
FinishGC(self, collector::kGcTypeNone);
return HomogeneousSpaceCompactResult::kErrorVMShuttingDown;
}
// Suspend all threads.
tl->SuspendAll();
uint64_t start_time = NanoTime();
// Launch compaction.
space::MallocSpace* to_space = main_space_backup_.release();
space::MallocSpace* from_space = main_space_;
to_space->GetMemMap()->Protect(PROT_READ | PROT_WRITE);
const uint64_t space_size_before_compaction = from_space->Size();
AddSpace(to_space);
// Make sure that we will have enough room to copy.
CHECK_GE(to_space->GetFootprintLimit(), from_space->GetFootprintLimit());
Compact(to_space, from_space, kGcCauseHomogeneousSpaceCompact);
// Leave as prot read so that we can still run ROSAlloc verification on this space.
from_space->GetMemMap()->Protect(PROT_READ);
const uint64_t space_size_after_compaction = to_space->Size();
main_space_ = to_space;
main_space_backup_.reset(from_space);
RemoveSpace(from_space);
SetSpaceAsDefault(main_space_); // Set as default to reset the proper dlmalloc space.
// Update performed homogeneous space compaction count.
count_performed_homogeneous_space_compaction_++;
// Print statics log and resume all threads.
uint64_t duration = NanoTime() - start_time;
VLOG(heap) << "Heap homogeneous space compaction took " << PrettyDuration(duration) << " size: "
<< PrettySize(space_size_before_compaction) << " -> "
<< PrettySize(space_size_after_compaction) << " compact-ratio: "
<< std::fixed << static_cast<double>(space_size_after_compaction) /
static_cast<double>(space_size_before_compaction);
tl->ResumeAll();
// Finish GC.
reference_processor_.EnqueueClearedReferences(self);
GrowForUtilization(semi_space_collector_);
FinishGC(self, collector::kGcTypeFull);
return HomogeneousSpaceCompactResult::kSuccess;
}
void Heap::TransitionCollector(CollectorType collector_type) {
if (collector_type == collector_type_) {
return;
}
VLOG(heap) << "TransitionCollector: " << static_cast<int>(collector_type_)
<< " -> " << static_cast<int>(collector_type);
uint64_t start_time = NanoTime();
uint32_t before_allocated = num_bytes_allocated_.LoadSequentiallyConsistent();
Runtime* const runtime = Runtime::Current();
ThreadList* const tl = runtime->GetThreadList();
Thread* const self = Thread::Current();
ScopedThreadStateChange tsc(self, kWaitingPerformingGc);
Locks::mutator_lock_->AssertNotHeld(self);
// Busy wait until we can GC (StartGC can fail if we have a non-zero
// compacting_gc_disable_count_, this should rarely occurs).
for (;;) {
{
ScopedThreadStateChange tsc(self, kWaitingForGcToComplete);
MutexLock mu(self, *gc_complete_lock_);
// Ensure there is only one GC at a time.
WaitForGcToCompleteLocked(kGcCauseCollectorTransition, self);
// Currently we only need a heap transition if we switch from a moving collector to a
// non-moving one, or visa versa.
const bool copying_transition = IsMovingGc(collector_type_) != IsMovingGc(collector_type);
// If someone else beat us to it and changed the collector before we could, exit.
// This is safe to do before the suspend all since we set the collector_type_running_ before
// we exit the loop. If another thread attempts to do the heap transition before we exit,
// then it would get blocked on WaitForGcToCompleteLocked.
if (collector_type == collector_type_) {
return;
}
// GC can be disabled if someone has a used GetPrimitiveArrayCritical but not yet released.
if (!copying_transition || disable_moving_gc_count_ == 0) {
// TODO: Not hard code in semi-space collector?
collector_type_running_ = copying_transition ? kCollectorTypeSS : collector_type;
break;
}
}
usleep(1000);
}
if (runtime->IsShuttingDown(self)) {
// Don't allow heap transitions to happen if the runtime is shutting down since these can
// cause objects to get finalized.
FinishGC(self, collector::kGcTypeNone);
return;
}
tl->SuspendAll();
switch (collector_type) {
case kCollectorTypeSS: {
if (!IsMovingGc(collector_type_)) {
// Create the bump pointer space from the backup space.
CHECK(main_space_backup_ != nullptr);
std::unique_ptr<MemMap> mem_map(main_space_backup_->ReleaseMemMap());
// We are transitioning from non moving GC -> moving GC, since we copied from the bump
// pointer space last transition it will be protected.
CHECK(mem_map != nullptr);
mem_map->Protect(PROT_READ | PROT_WRITE);
bump_pointer_space_ = space::BumpPointerSpace::CreateFromMemMap("Bump pointer space",
mem_map.release());
AddSpace(bump_pointer_space_);
Compact(bump_pointer_space_, main_space_, kGcCauseCollectorTransition);
// Use the now empty main space mem map for the bump pointer temp space.
mem_map.reset(main_space_->ReleaseMemMap());
// Unset the pointers just in case.
if (dlmalloc_space_ == main_space_) {
dlmalloc_space_ = nullptr;
} else if (rosalloc_space_ == main_space_) {
rosalloc_space_ = nullptr;
}
// Remove the main space so that we don't try to trim it, this doens't work for debug
// builds since RosAlloc attempts to read the magic number from a protected page.
RemoveSpace(main_space_);
RemoveRememberedSet(main_space_);
delete main_space_; // Delete the space since it has been removed.
main_space_ = nullptr;
RemoveRememberedSet(main_space_backup_.get());
main_space_backup_.reset(nullptr); // Deletes the space.
temp_space_ = space::BumpPointerSpace::CreateFromMemMap("Bump pointer space 2",
mem_map.release());
AddSpace(temp_space_);
}
break;
}
case kCollectorTypeMS:
// Fall through.
case kCollectorTypeCMS: {
if (IsMovingGc(collector_type_)) {
CHECK(temp_space_ != nullptr);
std::unique_ptr<MemMap> mem_map(temp_space_->ReleaseMemMap());
RemoveSpace(temp_space_);
temp_space_ = nullptr;
mem_map->Protect(PROT_READ | PROT_WRITE);
CreateMainMallocSpace(mem_map.get(), kDefaultInitialSize,
std::min(mem_map->Size(), growth_limit_), mem_map->Size());
mem_map.release();
// Compact to the main space from the bump pointer space, don't need to swap semispaces.
AddSpace(main_space_);
Compact(main_space_, bump_pointer_space_, kGcCauseCollectorTransition);
mem_map.reset(bump_pointer_space_->ReleaseMemMap());
RemoveSpace(bump_pointer_space_);
bump_pointer_space_ = nullptr;
const char* name = kUseRosAlloc ? kRosAllocSpaceName[1] : kDlMallocSpaceName[1];
// Temporarily unprotect the backup mem map so rosalloc can write the debug magic number.
if (kIsDebugBuild && kUseRosAlloc) {
mem_map->Protect(PROT_READ | PROT_WRITE);
}
main_space_backup_.reset(CreateMallocSpaceFromMemMap(
mem_map.get(), kDefaultInitialSize, std::min(mem_map->Size(), growth_limit_),
mem_map->Size(), name, true));
if (kIsDebugBuild && kUseRosAlloc) {
mem_map->Protect(PROT_NONE);
}
mem_map.release();
}
break;
}
default: {
LOG(FATAL) << "Attempted to transition to invalid collector type "
<< static_cast<size_t>(collector_type);
break;
}
}
ChangeCollector(collector_type);
tl->ResumeAll();
// Can't call into java code with all threads suspended.
reference_processor_.EnqueueClearedReferences(self);
uint64_t duration = NanoTime() - start_time;
GrowForUtilization(semi_space_collector_);
FinishGC(self, collector::kGcTypeFull);
int32_t after_allocated = num_bytes_allocated_.LoadSequentiallyConsistent();
int32_t delta_allocated = before_allocated - after_allocated;
std::string saved_str;
if (delta_allocated >= 0) {
saved_str = " saved at least " + PrettySize(delta_allocated);
} else {
saved_str = " expanded " + PrettySize(-delta_allocated);
}
VLOG(heap) << "Heap transition to " << process_state_ << " took "
<< PrettyDuration(duration) << saved_str;
}
void Heap::ChangeCollector(CollectorType collector_type) {
// TODO: Only do this with all mutators suspended to avoid races.
if (collector_type != collector_type_) {
if (collector_type == kCollectorTypeMC) {
// Don't allow mark compact unless support is compiled in.
CHECK(kMarkCompactSupport);
}
collector_type_ = collector_type;
gc_plan_.clear();
switch (collector_type_) {
case kCollectorTypeCC: // Fall-through.
case kCollectorTypeMC: // Fall-through.
case kCollectorTypeSS: // Fall-through.
case kCollectorTypeGSS: {
gc_plan_.push_back(collector::kGcTypeFull);
if (use_tlab_) {
ChangeAllocator(kAllocatorTypeTLAB);
} else {
ChangeAllocator(kAllocatorTypeBumpPointer);
}
break;
}
case kCollectorTypeMS: {
gc_plan_.push_back(collector::kGcTypeSticky);
gc_plan_.push_back(collector::kGcTypePartial);
gc_plan_.push_back(collector::kGcTypeFull);
ChangeAllocator(kUseRosAlloc ? kAllocatorTypeRosAlloc : kAllocatorTypeDlMalloc);
break;
}
case kCollectorTypeCMS: {
gc_plan_.push_back(collector::kGcTypeSticky);
gc_plan_.push_back(collector::kGcTypePartial);
gc_plan_.push_back(collector::kGcTypeFull);
ChangeAllocator(kUseRosAlloc ? kAllocatorTypeRosAlloc : kAllocatorTypeDlMalloc);
break;
}
default: {
LOG(FATAL) << "Unimplemented";
}
}
if (IsGcConcurrent()) {
concurrent_start_bytes_ =
std::max(max_allowed_footprint_, kMinConcurrentRemainingBytes) - kMinConcurrentRemainingBytes;
} else {
concurrent_start_bytes_ = std::numeric_limits<size_t>::max();
}
}
}
// Special compacting collector which uses sub-optimal bin packing to reduce zygote space size.
class ZygoteCompactingCollector FINAL : public collector::SemiSpace {
public:
explicit ZygoteCompactingCollector(gc::Heap* heap) : SemiSpace(heap, false, "zygote collector"),
bin_live_bitmap_(nullptr), bin_mark_bitmap_(nullptr) {
}
void BuildBins(space::ContinuousSpace* space) {
bin_live_bitmap_ = space->GetLiveBitmap();
bin_mark_bitmap_ = space->GetMarkBitmap();
BinContext context;
context.prev_ = reinterpret_cast<uintptr_t>(space->Begin());
context.collector_ = this;
WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
// Note: This requires traversing the space in increasing order of object addresses.
bin_live_bitmap_->Walk(Callback, reinterpret_cast<void*>(&context));
// Add the last bin which spans after the last object to the end of the space.
AddBin(reinterpret_cast<uintptr_t>(space->End()) - context.prev_, context.prev_);
}
private:
struct BinContext {
uintptr_t prev_; // The end of the previous object.
ZygoteCompactingCollector* collector_;
};
// Maps from bin sizes to locations.
std::multimap<size_t, uintptr_t> bins_;
// Live bitmap of the space which contains the bins.
accounting::ContinuousSpaceBitmap* bin_live_bitmap_;
// Mark bitmap of the space which contains the bins.
accounting::ContinuousSpaceBitmap* bin_mark_bitmap_;
static void Callback(mirror::Object* obj, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
DCHECK(arg != nullptr);
BinContext* context = reinterpret_cast<BinContext*>(arg);
ZygoteCompactingCollector* collector = context->collector_;
uintptr_t object_addr = reinterpret_cast<uintptr_t>(obj);
size_t bin_size = object_addr - context->prev_;
// Add the bin consisting of the end of the previous object to the start of the current object.
collector->AddBin(bin_size, context->prev_);
context->prev_ = object_addr + RoundUp(obj->SizeOf(), kObjectAlignment);
}
void AddBin(size_t size, uintptr_t position) {
if (size != 0) {
bins_.insert(std::make_pair(size, position));
}
}
virtual bool ShouldSweepSpace(space::ContinuousSpace* space) const {
// Don't sweep any spaces since we probably blasted the internal accounting of the free list
// allocator.
return false;
}
virtual mirror::Object* MarkNonForwardedObject(mirror::Object* obj)
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_) {
size_t object_size = RoundUp(obj->SizeOf(), kObjectAlignment);
mirror::Object* forward_address;
// Find the smallest bin which we can move obj in.
auto it = bins_.lower_bound(object_size);
if (it == bins_.end()) {
// No available space in the bins, place it in the target space instead (grows the zygote
// space).
size_t bytes_allocated;
forward_address = to_space_->Alloc(self_, object_size, &bytes_allocated, nullptr);
if (to_space_live_bitmap_ != nullptr) {
to_space_live_bitmap_->Set(forward_address);
} else {
GetHeap()->GetNonMovingSpace()->GetLiveBitmap()->Set(forward_address);
GetHeap()->GetNonMovingSpace()->GetMarkBitmap()->Set(forward_address);
}
} else {
size_t size = it->first;
uintptr_t pos = it->second;
bins_.erase(it); // Erase the old bin which we replace with the new smaller bin.
forward_address = reinterpret_cast<mirror::Object*>(pos);
// Set the live and mark bits so that sweeping system weaks works properly.
bin_live_bitmap_->Set(forward_address);
bin_mark_bitmap_->Set(forward_address);
DCHECK_GE(size, object_size);
AddBin(size - object_size, pos + object_size); // Add a new bin with the remaining space.
}
// Copy the object over to its new location.
memcpy(reinterpret_cast<void*>(forward_address), obj, object_size);
if (kUseBakerOrBrooksReadBarrier) {
obj->AssertReadBarrierPointer();
if (kUseBrooksReadBarrier) {
DCHECK_EQ(forward_address->GetReadBarrierPointer(), obj);
forward_address->SetReadBarrierPointer(forward_address);
}
forward_address->AssertReadBarrierPointer();
}
return forward_address;
}
};
void Heap::UnBindBitmaps() {
TimingLogger::ScopedTiming t("UnBindBitmaps", GetCurrentGcIteration()->GetTimings());
for (const auto& space : GetContinuousSpaces()) {
if (space->IsContinuousMemMapAllocSpace()) {
space::ContinuousMemMapAllocSpace* alloc_space = space->AsContinuousMemMapAllocSpace();
if (alloc_space->HasBoundBitmaps()) {
alloc_space->UnBindBitmaps();
}
}
}
}
void Heap::PreZygoteFork() {
CollectGarbageInternal(collector::kGcTypeFull, kGcCauseBackground, false);
Thread* self = Thread::Current();
MutexLock mu(self, zygote_creation_lock_);
// Try to see if we have any Zygote spaces.
if (have_zygote_space_) {
return;
}
Runtime::Current()->GetInternTable()->SwapPostZygoteWithPreZygote();
Runtime::Current()->GetClassLinker()->MoveClassTableToPreZygote();
VLOG(heap) << "Starting PreZygoteFork";
// Trim the pages at the end of the non moving space.
non_moving_space_->Trim();
// The end of the non-moving space may be protected, unprotect it so that we can copy the zygote
// there.
non_moving_space_->GetMemMap()->Protect(PROT_READ | PROT_WRITE);
const bool same_space = non_moving_space_ == main_space_;
if (kCompactZygote) {
// Can't compact if the non moving space is the same as the main space.
DCHECK(semi_space_collector_ != nullptr);
// Temporarily disable rosalloc verification because the zygote
// compaction will mess up the rosalloc internal metadata.
ScopedDisableRosAllocVerification disable_rosalloc_verif(this);
ZygoteCompactingCollector zygote_collector(this);
zygote_collector.BuildBins(non_moving_space_);
// Create a new bump pointer space which we will compact into.
space::BumpPointerSpace target_space("zygote bump space", non_moving_space_->End(),
non_moving_space_->Limit());
// Compact the bump pointer space to a new zygote bump pointer space.
bool reset_main_space = false;
if (IsMovingGc(collector_type_)) {
zygote_collector.SetFromSpace(bump_pointer_space_);
} else {
CHECK(main_space_ != nullptr);
// Copy from the main space.
zygote_collector.SetFromSpace(main_space_);
reset_main_space = true;
}
zygote_collector.SetToSpace(&target_space);
zygote_collector.SetSwapSemiSpaces(false);
zygote_collector.Run(kGcCauseCollectorTransition, false);
if (reset_main_space) {
main_space_->GetMemMap()->Protect(PROT_READ | PROT_WRITE);
madvise(main_space_->Begin(), main_space_->Capacity(), MADV_DONTNEED);
MemMap* mem_map = main_space_->ReleaseMemMap();
RemoveSpace(main_space_);
space::Space* old_main_space = main_space_;
CreateMainMallocSpace(mem_map, kDefaultInitialSize, std::min(mem_map->Size(), growth_limit_),
mem_map->Size());
delete old_main_space;
AddSpace(main_space_);
} else {
bump_pointer_space_->GetMemMap()->Protect(PROT_READ | PROT_WRITE);
}
if (temp_space_ != nullptr) {
CHECK(temp_space_->IsEmpty());
}
total_objects_freed_ever_ += GetCurrentGcIteration()->GetFreedObjects();
total_bytes_freed_ever_ += GetCurrentGcIteration()->GetFreedBytes();
// Update the end and write out image.
non_moving_space_->SetEnd(target_space.End());
non_moving_space_->SetLimit(target_space.Limit());
VLOG(heap) << "Zygote space size " << non_moving_space_->Size() << " bytes";
}
// Change the collector to the post zygote one.
ChangeCollector(foreground_collector_type_);
// Save the old space so that we can remove it after we complete creating the zygote space.
space::MallocSpace* old_alloc_space = non_moving_space_;
// Turn the current alloc space into a zygote space and obtain the new alloc space composed of
// the remaining available space.
// Remove the old space before creating the zygote space since creating the zygote space sets
// the old alloc space's bitmaps to nullptr.
RemoveSpace(old_alloc_space);
if (collector::SemiSpace::kUseRememberedSet) {
// Sanity bound check.
FindRememberedSetFromSpace(old_alloc_space)->AssertAllDirtyCardsAreWithinSpace();
// Remove the remembered set for the now zygote space (the old
// non-moving space). Note now that we have compacted objects into
// the zygote space, the data in the remembered set is no longer
// needed. The zygote space will instead have a mod-union table
// from this point on.
RemoveRememberedSet(old_alloc_space);
}
// Remaining space becomes the new non moving space.
space::ZygoteSpace* zygote_space = old_alloc_space->CreateZygoteSpace(kNonMovingSpaceName,
low_memory_mode_,
&non_moving_space_);
CHECK(!non_moving_space_->CanMoveObjects());
if (same_space) {
main_space_ = non_moving_space_;
SetSpaceAsDefault(main_space_);
}
delete old_alloc_space;
CHECK(zygote_space != nullptr) << "Failed creating zygote space";
AddSpace(zygote_space);
non_moving_space_->SetFootprintLimit(non_moving_space_->Capacity());
AddSpace(non_moving_space_);
have_zygote_space_ = true;
// Enable large object space allocations.
large_object_threshold_ = kDefaultLargeObjectThreshold;
// Create the zygote space mod union table.
accounting::ModUnionTable* mod_union_table =
new accounting::ModUnionTableCardCache("zygote space mod-union table", this, zygote_space);
CHECK(mod_union_table != nullptr) << "Failed to create zygote space mod-union table";
AddModUnionTable(mod_union_table);
if (collector::SemiSpace::kUseRememberedSet) {
// Add a new remembered set for the post-zygote non-moving space.
accounting::RememberedSet* post_zygote_non_moving_space_rem_set =
new accounting::RememberedSet("Post-zygote non-moving space remembered set", this,
non_moving_space_);
CHECK(post_zygote_non_moving_space_rem_set != nullptr)
<< "Failed to create post-zygote non-moving space remembered set";
AddRememberedSet(post_zygote_non_moving_space_rem_set);
}
}
void Heap::FlushAllocStack() {
MarkAllocStackAsLive(allocation_stack_.get());
allocation_stack_->Reset();
}
void Heap::MarkAllocStack(accounting::ContinuousSpaceBitmap* bitmap1,
accounting::ContinuousSpaceBitmap* bitmap2,
accounting::LargeObjectBitmap* large_objects,
accounting::ObjectStack* stack) {
DCHECK(bitmap1 != nullptr);
DCHECK(bitmap2 != nullptr);
mirror::Object** limit = stack->End();
for (mirror::Object** it = stack->Begin(); it != limit; ++it) {
const mirror::Object* obj = *it;
if (!kUseThreadLocalAllocationStack || obj != nullptr) {
if (bitmap1->HasAddress(obj)) {
bitmap1->Set(obj);
} else if (bitmap2->HasAddress(obj)) {
bitmap2->Set(obj);
} else {
large_objects->Set(obj);
}
}
}
}
void Heap::SwapSemiSpaces() {
CHECK(bump_pointer_space_ != nullptr);
CHECK(temp_space_ != nullptr);
std::swap(bump_pointer_space_, temp_space_);
}
void Heap::Compact(space::ContinuousMemMapAllocSpace* target_space,
space::ContinuousMemMapAllocSpace* source_space,
GcCause gc_cause) {
CHECK(kMovingCollector);
if (target_space != source_space) {
// Don't swap spaces since this isn't a typical semi space collection.
semi_space_collector_->SetSwapSemiSpaces(false);
semi_space_collector_->SetFromSpace(source_space);
semi_space_collector_->SetToSpace(target_space);
semi_space_collector_->Run(gc_cause, false);
} else {
CHECK(target_space->IsBumpPointerSpace())
<< "In-place compaction is only supported for bump pointer spaces";
mark_compact_collector_->SetSpace(target_space->AsBumpPointerSpace());
mark_compact_collector_->Run(kGcCauseCollectorTransition, false);
}
}
collector::GcType Heap::CollectGarbageInternal(collector::GcType gc_type, GcCause gc_cause,
bool clear_soft_references) {
Thread* self = Thread::Current();
Runtime* runtime = Runtime::Current();
// If the heap can't run the GC, silently fail and return that no GC was run.
switch (gc_type) {
case collector::kGcTypePartial: {
if (!have_zygote_space_) {
return collector::kGcTypeNone;
}
break;
}
default: {
// Other GC types don't have any special cases which makes them not runnable. The main case
// here is full GC.
}
}
ScopedThreadStateChange tsc(self, kWaitingPerformingGc);
Locks::mutator_lock_->AssertNotHeld(self);
if (self->IsHandlingStackOverflow()) {
LOG(WARNING) << "Performing GC on a thread that is handling a stack overflow.";
}
bool compacting_gc;
{
gc_complete_lock_->AssertNotHeld(self);
ScopedThreadStateChange tsc(self, kWaitingForGcToComplete);
MutexLock mu(self, *gc_complete_lock_);
// Ensure there is only one GC at a time.
WaitForGcToCompleteLocked(gc_cause, self);
compacting_gc = IsMovingGc(collector_type_);
// GC can be disabled if someone has a used GetPrimitiveArrayCritical.
if (compacting_gc && disable_moving_gc_count_ != 0) {
LOG(WARNING) << "Skipping GC due to disable moving GC count " << disable_moving_gc_count_;
return collector::kGcTypeNone;
}
collector_type_running_ = collector_type_;
}
if (gc_cause == kGcCauseForAlloc && runtime->HasStatsEnabled()) {
++runtime->GetStats()->gc_for_alloc_count;
++self->GetStats()->gc_for_alloc_count;
}
uint64_t gc_start_time_ns = NanoTime();
uint64_t gc_start_size = GetBytesAllocated();
// Approximate allocation rate in bytes / second.
uint64_t ms_delta = NsToMs(gc_start_time_ns - last_gc_time_ns_);
// Back to back GCs can cause 0 ms of wait time in between GC invocations.
if (LIKELY(ms_delta != 0)) {
allocation_rate_ = ((gc_start_size - last_gc_size_) * 1000) / ms_delta;
ATRACE_INT("Allocation rate KB/s", allocation_rate_ / KB);
VLOG(heap) << "Allocation rate: " << PrettySize(allocation_rate_) << "/s";
}
DCHECK_LT(gc_type, collector::kGcTypeMax);
DCHECK_NE(gc_type, collector::kGcTypeNone);
collector::GarbageCollector* collector = nullptr;
// TODO: Clean this up.
if (compacting_gc) {
DCHECK(current_allocator_ == kAllocatorTypeBumpPointer ||
current_allocator_ == kAllocatorTypeTLAB);
switch (collector_type_) {
case kCollectorTypeSS:
// Fall-through.
case kCollectorTypeGSS:
semi_space_collector_->SetFromSpace(bump_pointer_space_);
semi_space_collector_->SetToSpace(temp_space_);
semi_space_collector_->SetSwapSemiSpaces(true);
collector = semi_space_collector_;
break;
case kCollectorTypeCC:
collector = concurrent_copying_collector_;
break;
case kCollectorTypeMC:
mark_compact_collector_->SetSpace(bump_pointer_space_);
collector = mark_compact_collector_;
break;
default:
LOG(FATAL) << "Invalid collector type " << static_cast<size_t>(collector_type_);
}
if (collector != mark_compact_collector_) {
temp_space_->GetMemMap()->Protect(PROT_READ | PROT_WRITE);
CHECK(temp_space_->IsEmpty());
}
gc_type = collector::kGcTypeFull; // TODO: Not hard code this in.
} else if (current_allocator_ == kAllocatorTypeRosAlloc ||
current_allocator_ == kAllocatorTypeDlMalloc) {
collector = FindCollectorByGcType(gc_type);
} else {
LOG(FATAL) << "Invalid current allocator " << current_allocator_;
}
if (IsGcConcurrent()) {
// Disable concurrent GC check so that we don't have spammy JNI requests.
// This gets recalculated in GrowForUtilization. It is important that it is disabled /
// calculated in the same thread so that there aren't any races that can cause it to become
// permanantly disabled. b/17942071
concurrent_start_bytes_ = std::numeric_limits<size_t>::max();
}
CHECK(collector != nullptr)
<< "Could not find garbage collector with collector_type="
<< static_cast<size_t>(collector_type_) << " and gc_type=" << gc_type;
collector->Run(gc_cause, clear_soft_references || runtime->IsZygote());
total_objects_freed_ever_ += GetCurrentGcIteration()->GetFreedObjects();
total_bytes_freed_ever_ += GetCurrentGcIteration()->GetFreedBytes();
RequestHeapTrim();
// Enqueue cleared references.
reference_processor_.EnqueueClearedReferences(self);
// Grow the heap so that we know when to perform the next GC.
GrowForUtilization(collector);
const size_t duration = GetCurrentGcIteration()->GetDurationNs();
const std::vector<uint64_t>& pause_times = GetCurrentGcIteration()->GetPauseTimes();
// Print the GC if it is an explicit GC (e.g. Runtime.gc()) or a slow GC
// (mutator time blocked >= long_pause_log_threshold_).
bool log_gc = gc_cause == kGcCauseExplicit;
if (!log_gc && CareAboutPauseTimes()) {
// GC for alloc pauses the allocating thread, so consider it as a pause.
log_gc = duration > long_gc_log_threshold_ ||
(gc_cause == kGcCauseForAlloc && duration > long_pause_log_threshold_);
for (uint64_t pause : pause_times) {
log_gc = log_gc || pause >= long_pause_log_threshold_;
}
}
if (log_gc) {
const size_t percent_free = GetPercentFree();
const size_t current_heap_size = GetBytesAllocated();
const size_t total_memory = GetTotalMemory();
std::ostringstream pause_string;
for (size_t i = 0; i < pause_times.size(); ++i) {
pause_string << PrettyDuration((pause_times[i] / 1000) * 1000)
<< ((i != pause_times.size() - 1) ? "," : "");
}
LOG(INFO) << gc_cause << " " << collector->GetName()
<< " GC freed " << current_gc_iteration_.GetFreedObjects() << "("
<< PrettySize(current_gc_iteration_.GetFreedBytes()) << ") AllocSpace objects, "
<< current_gc_iteration_.GetFreedLargeObjects() << "("
<< PrettySize(current_gc_iteration_.GetFreedLargeObjectBytes()) << ") LOS objects, "
<< percent_free << "% free, " << PrettySize(current_heap_size) << "/"
<< PrettySize(total_memory) << ", " << "paused " << pause_string.str()
<< " total " << PrettyDuration((duration / 1000) * 1000);
VLOG(heap) << ConstDumpable<TimingLogger>(*current_gc_iteration_.GetTimings());
}
FinishGC(self, gc_type);
// Inform DDMS that a GC completed.
Dbg::GcDidFinish();
return gc_type;
}
void Heap::FinishGC(Thread* self, collector::GcType gc_type) {
MutexLock mu(self, *gc_complete_lock_);
collector_type_running_ = kCollectorTypeNone;
if (gc_type != collector::kGcTypeNone) {
last_gc_type_ = gc_type;
}
// Wake anyone who may have been waiting for the GC to complete.
gc_complete_cond_->Broadcast(self);
}
static void RootMatchesObjectVisitor(mirror::Object** root, void* arg,
const RootInfo& /*root_info*/) {
mirror::Object* obj = reinterpret_cast<mirror::Object*>(arg);
if (*root == obj) {
LOG(INFO) << "Object " << obj << " is a root";
}
}
class ScanVisitor {
public:
void operator()(const mirror::Object* obj) const {
LOG(ERROR) << "Would have rescanned object " << obj;
}
};
// Verify a reference from an object.
class VerifyReferenceVisitor {
public:
explicit VerifyReferenceVisitor(Heap* heap, Atomic<size_t>* fail_count, bool verify_referent)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_)
: heap_(heap), fail_count_(fail_count), verify_referent_(verify_referent) {}
size_t GetFailureCount() const {
return fail_count_->LoadSequentiallyConsistent();
}
void operator()(mirror::Class* klass, mirror::Reference* ref) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
if (verify_referent_) {
VerifyReference(ref, ref->GetReferent(), mirror::Reference::ReferentOffset());
}
}
void operator()(mirror::Object* obj, MemberOffset offset, bool /*is_static*/) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
VerifyReference(obj, obj->GetFieldObject<mirror::Object>(offset), offset);
}
bool IsLive(mirror::Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
return heap_->IsLiveObjectLocked(obj, true, false, true);
}
static void VerifyRootCallback(mirror::Object** root, void* arg, const RootInfo& root_info)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
VerifyReferenceVisitor* visitor = reinterpret_cast<VerifyReferenceVisitor*>(arg);
if (!visitor->VerifyReference(nullptr, *root, MemberOffset(0))) {
LOG(ERROR) << "Root " << *root << " is dead with type " << PrettyTypeOf(*root)
<< " thread_id= " << root_info.GetThreadId() << " root_type= " << root_info.GetType();
}
}
private:
// TODO: Fix the no thread safety analysis.
// Returns false on failure.
bool VerifyReference(mirror::Object* obj, mirror::Object* ref, MemberOffset offset) const
NO_THREAD_SAFETY_ANALYSIS {
if (ref == nullptr || IsLive(ref)) {
// Verify that the reference is live.
return true;
}
if (fail_count_->FetchAndAddSequentiallyConsistent(1) == 0) {
// Print message on only on first failure to prevent spam.
LOG(ERROR) << "!!!!!!!!!!!!!!Heap corruption detected!!!!!!!!!!!!!!!!!!!";
}
if (obj != nullptr) {
// Only do this part for non roots.
accounting::CardTable* card_table = heap_->GetCardTable();
accounting::ObjectStack* alloc_stack = heap_->allocation_stack_.get();
accounting::ObjectStack* live_stack = heap_->live_stack_.get();
byte* card_addr = card_table->CardFromAddr(obj);
LOG(ERROR) << "Object " << obj << " references dead object " << ref << " at offset "
<< offset << "\n card value = " << static_cast<int>(*card_addr);
if (heap_->IsValidObjectAddress(obj->GetClass())) {
LOG(ERROR) << "Obj type " << PrettyTypeOf(obj);
} else {
LOG(ERROR) << "Object " << obj << " class(" << obj->GetClass() << ") not a heap address";
}
// Attempt to find the class inside of the recently freed objects.
space::ContinuousSpace* ref_space = heap_->FindContinuousSpaceFromObject(ref, true);
if (ref_space != nullptr && ref_space->IsMallocSpace()) {
space::MallocSpace* space = ref_space->AsMallocSpace();
mirror::Class* ref_class = space->FindRecentFreedObject(ref);
if (ref_class != nullptr) {
LOG(ERROR) << "Reference " << ref << " found as a recently freed object with class "
<< PrettyClass(ref_class);
} else {
LOG(ERROR) << "Reference " << ref << " not found as a recently freed object";
}
}
if (ref->GetClass() != nullptr && heap_->IsValidObjectAddress(ref->GetClass()) &&
ref->GetClass()->IsClass()) {
LOG(ERROR) << "Ref type " << PrettyTypeOf(ref);
} else {
LOG(ERROR) << "Ref " << ref << " class(" << ref->GetClass()
<< ") is not a valid heap address";
}
card_table->CheckAddrIsInCardTable(reinterpret_cast<const byte*>(obj));
void* cover_begin = card_table->AddrFromCard(card_addr);
void* cover_end = reinterpret_cast<void*>(reinterpret_cast<size_t>(cover_begin) +
accounting::CardTable::kCardSize);
LOG(ERROR) << "Card " << reinterpret_cast<void*>(card_addr) << " covers " << cover_begin
<< "-" << cover_end;
accounting::ContinuousSpaceBitmap* bitmap =
heap_->GetLiveBitmap()->GetContinuousSpaceBitmap(obj);
if (bitmap == nullptr) {
LOG(ERROR) << "Object " << obj << " has no bitmap";
if (!VerifyClassClass(obj->GetClass())) {
LOG(ERROR) << "Object " << obj << " failed class verification!";
}
} else {
// Print out how the object is live.
if (bitmap->Test(obj)) {
LOG(ERROR) << "Object " << obj << " found in live bitmap";
}
if (alloc_stack->Contains(const_cast<mirror::Object*>(obj))) {
LOG(ERROR) << "Object " << obj << " found in allocation stack";
}
if (live_stack->Contains(const_cast<mirror::Object*>(obj))) {
LOG(ERROR) << "Object " << obj << " found in live stack";
}
if (alloc_stack->Contains(const_cast<mirror::Object*>(ref))) {
LOG(ERROR) << "Ref " << ref << " found in allocation stack";
}
if (live_stack->Contains(const_cast<mirror::Object*>(ref))) {
LOG(ERROR) << "Ref " << ref << " found in live stack";
}
// Attempt to see if the card table missed the reference.
ScanVisitor scan_visitor;
byte* byte_cover_begin = reinterpret_cast<byte*>(card_table->AddrFromCard(card_addr));
card_table->Scan(bitmap, byte_cover_begin,
byte_cover_begin + accounting::CardTable::kCardSize, scan_visitor);
}
// Search to see if any of the roots reference our object.
void* arg = const_cast<void*>(reinterpret_cast<const void*>(obj));
Runtime::Current()->VisitRoots(&RootMatchesObjectVisitor, arg);
// Search to see if any of the roots reference our reference.
arg = const_cast<void*>(reinterpret_cast<const void*>(ref));
Runtime::Current()->VisitRoots(&RootMatchesObjectVisitor, arg);
}
return false;
}
Heap* const heap_;
Atomic<size_t>* const fail_count_;
const bool verify_referent_;
};
// Verify all references within an object, for use with HeapBitmap::Visit.
class VerifyObjectVisitor {
public:
explicit VerifyObjectVisitor(Heap* heap, Atomic<size_t>* fail_count, bool verify_referent)
: heap_(heap), fail_count_(fail_count), verify_referent_(verify_referent) {
}
void operator()(mirror::Object* obj) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
// Note: we are verifying the references in obj but not obj itself, this is because obj must
// be live or else how did we find it in the live bitmap?
VerifyReferenceVisitor visitor(heap_, fail_count_, verify_referent_);
// The class doesn't count as a reference but we should verify it anyways.
obj->VisitReferences<true>(visitor, visitor);
}
static void VisitCallback(mirror::Object* obj, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
VerifyObjectVisitor* visitor = reinterpret_cast<VerifyObjectVisitor*>(arg);
visitor->operator()(obj);
}
size_t GetFailureCount() const {
return fail_count_->LoadSequentiallyConsistent();
}
private:
Heap* const heap_;
Atomic<size_t>* const fail_count_;
const bool verify_referent_;
};
void Heap::PushOnAllocationStackWithInternalGC(Thread* self, mirror::Object** obj) {
// Slow path, the allocation stack push back must have already failed.
DCHECK(!allocation_stack_->AtomicPushBack(*obj));
do {
// TODO: Add handle VerifyObject.
StackHandleScope<1> hs(self);
HandleWrapper<mirror::Object> wrapper(hs.NewHandleWrapper(obj));
// Push our object into the reserve region of the allocaiton stack. This is only required due
// to heap verification requiring that roots are live (either in the live bitmap or in the
// allocation stack).
CHECK(allocation_stack_->AtomicPushBackIgnoreGrowthLimit(*obj));
CollectGarbageInternal(collector::kGcTypeSticky, kGcCauseForAlloc, false);
} while (!allocation_stack_->AtomicPushBack(*obj));
}
void Heap::PushOnThreadLocalAllocationStackWithInternalGC(Thread* self, mirror::Object** obj) {
// Slow path, the allocation stack push back must have already failed.
DCHECK(!self->PushOnThreadLocalAllocationStack(*obj));
mirror::Object** start_address;
mirror::Object** end_address;
while (!allocation_stack_->AtomicBumpBack(kThreadLocalAllocationStackSize, &start_address,
&end_address)) {
// TODO: Add handle VerifyObject.
StackHandleScope<1> hs(self);
HandleWrapper<mirror::Object> wrapper(hs.NewHandleWrapper(obj));
// Push our object into the reserve region of the allocaiton stack. This is only required due
// to heap verification requiring that roots are live (either in the live bitmap or in the
// allocation stack).
CHECK(allocation_stack_->AtomicPushBackIgnoreGrowthLimit(*obj));
// Push into the reserve allocation stack.
CollectGarbageInternal(collector::kGcTypeSticky, kGcCauseForAlloc, false);
}
self->SetThreadLocalAllocationStack(start_address, end_address);
// Retry on the new thread-local allocation stack.
CHECK(self->PushOnThreadLocalAllocationStack(*obj)); // Must succeed.
}
// Must do this with mutators suspended since we are directly accessing the allocation stacks.
size_t Heap::VerifyHeapReferences(bool verify_referents) {
Thread* self = Thread::Current();
Locks::mutator_lock_->AssertExclusiveHeld(self);
// Lets sort our allocation stacks so that we can efficiently binary search them.
allocation_stack_->Sort();
live_stack_->Sort();
// Since we sorted the allocation stack content, need to revoke all
// thread-local allocation stacks.
RevokeAllThreadLocalAllocationStacks(self);
Atomic<size_t> fail_count_(0);
VerifyObjectVisitor visitor(this, &fail_count_, verify_referents);
// Verify objects in the allocation stack since these will be objects which were:
// 1. Allocated prior to the GC (pre GC verification).
// 2. Allocated during the GC (pre sweep GC verification).
// We don't want to verify the objects in the live stack since they themselves may be
// pointing to dead objects if they are not reachable.
VisitObjects(VerifyObjectVisitor::VisitCallback, &visitor);
// Verify the roots:
Runtime::Current()->VisitRoots(VerifyReferenceVisitor::VerifyRootCallback, &visitor);
if (visitor.GetFailureCount() > 0) {
// Dump mod-union tables.
for (const auto& table_pair : mod_union_tables_) {
accounting::ModUnionTable* mod_union_table = table_pair.second;
mod_union_table->Dump(LOG(ERROR) << mod_union_table->GetName() << ": ");
}
// Dump remembered sets.
for (const auto& table_pair : remembered_sets_) {
accounting::RememberedSet* remembered_set = table_pair.second;
remembered_set->Dump(LOG(ERROR) << remembered_set->GetName() << ": ");
}
DumpSpaces(LOG(ERROR));
}
return visitor.GetFailureCount();
}
class VerifyReferenceCardVisitor {
public:
VerifyReferenceCardVisitor(Heap* heap, bool* failed)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_,
Locks::heap_bitmap_lock_)
: heap_(heap), failed_(failed) {
}
// TODO: Fix lock analysis to not use NO_THREAD_SAFETY_ANALYSIS, requires support for
// annotalysis on visitors.
void operator()(mirror::Object* obj, MemberOffset offset, bool is_static) const
NO_THREAD_SAFETY_ANALYSIS {
mirror::Object* ref = obj->GetFieldObject<mirror::Object>(offset);
// Filter out class references since changing an object's class does not mark the card as dirty.
// Also handles large objects, since the only reference they hold is a class reference.
if (ref != nullptr && !ref->IsClass()) {
accounting::CardTable* card_table = heap_->GetCardTable();
// If the object is not dirty and it is referencing something in the live stack other than
// class, then it must be on a dirty card.
if (!card_table->AddrIsInCardTable(obj)) {
LOG(ERROR) << "Object " << obj << " is not in the address range of the card table";
*failed_ = true;
} else if (!card_table->IsDirty(obj)) {
// TODO: Check mod-union tables.
// Card should be either kCardDirty if it got re-dirtied after we aged it, or
// kCardDirty - 1 if it didnt get touched since we aged it.
accounting::ObjectStack* live_stack = heap_->live_stack_.get();
if (live_stack->ContainsSorted(ref)) {
if (live_stack->ContainsSorted(obj)) {
LOG(ERROR) << "Object " << obj << " found in live stack";
}
if (heap_->GetLiveBitmap()->Test(obj)) {
LOG(ERROR) << "Object " << obj << " found in live bitmap";
}
LOG(ERROR) << "Object " << obj << " " << PrettyTypeOf(obj)
<< " references " << ref << " " << PrettyTypeOf(ref) << " in live stack";
// Print which field of the object is dead.
if (!obj->IsObjectArray()) {
mirror::Class* klass = is_static ? obj->AsClass() : obj->GetClass();
CHECK(klass != NULL);
mirror::ObjectArray<mirror::ArtField>* fields = is_static ? klass->GetSFields()
: klass->GetIFields();
CHECK(fields != NULL);
for (int32_t i = 0; i < fields->GetLength(); ++i) {
mirror::ArtField* cur = fields->Get(i);
if (cur->GetOffset().Int32Value() == offset.Int32Value()) {
LOG(ERROR) << (is_static ? "Static " : "") << "field in the live stack is "
<< PrettyField(cur);
break;
}
}
} else {
mirror::ObjectArray<mirror::Object>* object_array =
obj->AsObjectArray<mirror::Object>();
for (int32_t i = 0; i < object_array->GetLength(); ++i) {
if (object_array->Get(i) == ref) {
LOG(ERROR) << (is_static ? "Static " : "") << "obj[" << i << "] = ref";
}
}
}
*failed_ = true;
}
}
}
}
private:
Heap* const heap_;
bool* const failed_;
};
class VerifyLiveStackReferences {
public:
explicit VerifyLiveStackReferences(Heap* heap)
: heap_(heap),
failed_(false) {}
void operator()(mirror::Object* obj) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
VerifyReferenceCardVisitor visitor(heap_, const_cast<bool*>(&failed_));
obj->VisitReferences<true>(visitor, VoidFunctor());
}
bool Failed() const {
return failed_;
}
private:
Heap* const heap_;
bool failed_;
};
bool Heap::VerifyMissingCardMarks() {
Thread* self = Thread::Current();
Locks::mutator_lock_->AssertExclusiveHeld(self);
// We need to sort the live stack since we binary search it.
live_stack_->Sort();
// Since we sorted the allocation stack content, need to revoke all
// thread-local allocation stacks.
RevokeAllThreadLocalAllocationStacks(self);
VerifyLiveStackReferences visitor(this);
GetLiveBitmap()->Visit(visitor);
// We can verify objects in the live stack since none of these should reference dead objects.
for (mirror::Object** it = live_stack_->Begin(); it != live_stack_->End(); ++it) {
if (!kUseThreadLocalAllocationStack || *it != nullptr) {
visitor(*it);
}
}
return !visitor.Failed();
}
void Heap::SwapStacks(Thread* self) {
if (kUseThreadLocalAllocationStack) {
live_stack_->AssertAllZero();
}
allocation_stack_.swap(live_stack_);
}
void Heap::RevokeAllThreadLocalAllocationStacks(Thread* self) {
// This must be called only during the pause.
CHECK(Locks::mutator_lock_->IsExclusiveHeld(self));
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
MutexLock mu2(self, *Locks::thread_list_lock_);
std::list<Thread*> thread_list = Runtime::Current()->GetThreadList()->GetList();
for (Thread* t : thread_list) {
t->RevokeThreadLocalAllocationStack();
}
}
void Heap::AssertAllBumpPointerSpaceThreadLocalBuffersAreRevoked() {
if (kIsDebugBuild) {
if (bump_pointer_space_ != nullptr) {
bump_pointer_space_->AssertAllThreadLocalBuffersAreRevoked();
}
}
}
accounting::ModUnionTable* Heap::FindModUnionTableFromSpace(space::Space* space) {
auto it = mod_union_tables_.find(space);
if (it == mod_union_tables_.end()) {
return nullptr;
}
return it->second;
}
accounting::RememberedSet* Heap::FindRememberedSetFromSpace(space::Space* space) {
auto it = remembered_sets_.find(space);
if (it == remembered_sets_.end()) {
return nullptr;
}
return it->second;
}
void Heap::ProcessCards(TimingLogger* timings, bool use_rem_sets) {
TimingLogger::ScopedTiming t(__FUNCTION__, timings);
// Clear cards and keep track of cards cleared in the mod-union table.
for (const auto& space : continuous_spaces_) {
accounting::ModUnionTable* table = FindModUnionTableFromSpace(space);
accounting::RememberedSet* rem_set = FindRememberedSetFromSpace(space);
if (table != nullptr) {
const char* name = space->IsZygoteSpace() ? "ZygoteModUnionClearCards" :
"ImageModUnionClearCards";
TimingLogger::ScopedTiming t(name, timings);
table->ClearCards();
} else if (use_rem_sets && rem_set != nullptr) {
DCHECK(collector::SemiSpace::kUseRememberedSet && collector_type_ == kCollectorTypeGSS)
<< static_cast<int>(collector_type_);
TimingLogger::ScopedTiming t("AllocSpaceRemSetClearCards", timings);
rem_set->ClearCards();
} else if (space->GetType() != space::kSpaceTypeBumpPointerSpace) {
TimingLogger::ScopedTiming t("AllocSpaceClearCards", timings);
// No mod union table for the AllocSpace. Age the cards so that the GC knows that these cards
// were dirty before the GC started.
// TODO: Need to use atomic for the case where aged(cleaning thread) -> dirty(other thread)
// -> clean(cleaning thread).
// The races are we either end up with: Aged card, unaged card. Since we have the checkpoint
// roots and then we scan / update mod union tables after. We will always scan either card.
// If we end up with the non aged card, we scan it it in the pause.
card_table_->ModifyCardsAtomic(space->Begin(), space->End(), AgeCardVisitor(),
VoidFunctor());
}
}
}
static void IdentityMarkHeapReferenceCallback(mirror::HeapReference<mirror::Object>*, void*) {
}
void Heap::PreGcVerificationPaused(collector::GarbageCollector* gc) {
Thread* const self = Thread::Current();
TimingLogger* const timings = current_gc_iteration_.GetTimings();
TimingLogger::ScopedTiming t(__FUNCTION__, timings);
if (verify_pre_gc_heap_) {
TimingLogger::ScopedTiming t("(Paused)PreGcVerifyHeapReferences", timings);
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
size_t failures = VerifyHeapReferences();
if (failures > 0) {
LOG(FATAL) << "Pre " << gc->GetName() << " heap verification failed with " << failures
<< " failures";
}
}
// Check that all objects which reference things in the live stack are on dirty cards.
if (verify_missing_card_marks_) {
TimingLogger::ScopedTiming t("(Paused)PreGcVerifyMissingCardMarks", timings);
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
SwapStacks(self);
// Sort the live stack so that we can quickly binary search it later.
CHECK(VerifyMissingCardMarks()) << "Pre " << gc->GetName()
<< " missing card mark verification failed\n" << DumpSpaces();
SwapStacks(self);
}
if (verify_mod_union_table_) {
TimingLogger::ScopedTiming t("(Paused)PreGcVerifyModUnionTables", timings);
ReaderMutexLock reader_lock(self, *Locks::heap_bitmap_lock_);
for (const auto& table_pair : mod_union_tables_) {
accounting::ModUnionTable* mod_union_table = table_pair.second;
mod_union_table->UpdateAndMarkReferences(IdentityMarkHeapReferenceCallback, nullptr);
mod_union_table->Verify();
}
}
}
void Heap::PreGcVerification(collector::GarbageCollector* gc) {
if (verify_pre_gc_heap_ || verify_missing_card_marks_ || verify_mod_union_table_) {
collector::GarbageCollector::ScopedPause pause(gc);
PreGcVerificationPaused(gc);
}
}
void Heap::PrePauseRosAllocVerification(collector::GarbageCollector* gc) {
// TODO: Add a new runtime option for this?
if (verify_pre_gc_rosalloc_) {
RosAllocVerification(current_gc_iteration_.GetTimings(), "PreGcRosAllocVerification");
}
}
void Heap::PreSweepingGcVerification(collector::GarbageCollector* gc) {
Thread* const self = Thread::Current();
TimingLogger* const timings = current_gc_iteration_.GetTimings();
TimingLogger::ScopedTiming t(__FUNCTION__, timings);
// Called before sweeping occurs since we want to make sure we are not going so reclaim any
// reachable objects.
if (verify_pre_sweeping_heap_) {
TimingLogger::ScopedTiming t("(Paused)PostSweepingVerifyHeapReferences", timings);
CHECK_NE(self->GetState(), kRunnable);
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
// Swapping bound bitmaps does nothing.
gc->SwapBitmaps();
// Pass in false since concurrent reference processing can mean that the reference referents
// may point to dead objects at the point which PreSweepingGcVerification is called.
size_t failures = VerifyHeapReferences(false);
if (failures > 0) {
LOG(FATAL) << "Pre sweeping " << gc->GetName() << " GC verification failed with " << failures
<< " failures";
}
gc->SwapBitmaps();
}
if (verify_pre_sweeping_rosalloc_) {
RosAllocVerification(timings, "PreSweepingRosAllocVerification");
}
}
void Heap::PostGcVerificationPaused(collector::GarbageCollector* gc) {
// Only pause if we have to do some verification.
Thread* const self = Thread::Current();
TimingLogger* const timings = GetCurrentGcIteration()->GetTimings();
TimingLogger::ScopedTiming t(__FUNCTION__, timings);
if (verify_system_weaks_) {
ReaderMutexLock mu2(self, *Locks::heap_bitmap_lock_);
collector::MarkSweep* mark_sweep = down_cast<collector::MarkSweep*>(gc);
mark_sweep->VerifySystemWeaks();
}
if (verify_post_gc_rosalloc_) {
RosAllocVerification(timings, "(Paused)PostGcRosAllocVerification");
}
if (verify_post_gc_heap_) {
TimingLogger::ScopedTiming t("(Paused)PostGcVerifyHeapReferences", timings);
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
size_t failures = VerifyHeapReferences();
if (failures > 0) {
LOG(FATAL) << "Pre " << gc->GetName() << " heap verification failed with " << failures
<< " failures";
}
}
}
void Heap::PostGcVerification(collector::GarbageCollector* gc) {
if (verify_system_weaks_ || verify_post_gc_rosalloc_ || verify_post_gc_heap_) {
collector::GarbageCollector::ScopedPause pause(gc);
PostGcVerificationPaused(gc);
}
}
void Heap::RosAllocVerification(TimingLogger* timings, const char* name) {
TimingLogger::ScopedTiming t(name, timings);
for (const auto& space : continuous_spaces_) {
if (space->IsRosAllocSpace()) {
VLOG(heap) << name << " : " << space->GetName();
space->AsRosAllocSpace()->Verify();
}
}
}
collector::GcType Heap::WaitForGcToComplete(GcCause cause, Thread* self) {
ScopedThreadStateChange tsc(self, kWaitingForGcToComplete);
MutexLock mu(self, *gc_complete_lock_);
return WaitForGcToCompleteLocked(cause, self);
}
collector::GcType Heap::WaitForGcToCompleteLocked(GcCause cause, Thread* self) {
collector::GcType last_gc_type = collector::kGcTypeNone;
uint64_t wait_start = NanoTime();
while (collector_type_running_ != kCollectorTypeNone) {
ATRACE_BEGIN("GC: Wait For Completion");
// We must wait, change thread state then sleep on gc_complete_cond_;
gc_complete_cond_->Wait(self);
last_gc_type = last_gc_type_;
ATRACE_END();
}
uint64_t wait_time = NanoTime() - wait_start;
total_wait_time_ += wait_time;
if (wait_time > long_pause_log_threshold_) {
LOG(INFO) << "WaitForGcToComplete blocked for " << PrettyDuration(wait_time)
<< " for cause " << cause;
}
return last_gc_type;
}
void Heap::DumpForSigQuit(std::ostream& os) {
os << "Heap: " << GetPercentFree() << "% free, " << PrettySize(GetBytesAllocated()) << "/"
<< PrettySize(GetTotalMemory()) << "; " << GetObjectsAllocated() << " objects\n";
DumpGcPerformanceInfo(os);
}
size_t Heap::GetPercentFree() {
return static_cast<size_t>(100.0f * static_cast<float>(GetFreeMemory()) / max_allowed_footprint_);
}
void Heap::SetIdealFootprint(size_t max_allowed_footprint) {
if (max_allowed_footprint > GetMaxMemory()) {
VLOG(gc) << "Clamp target GC heap from " << PrettySize(max_allowed_footprint) << " to "
<< PrettySize(GetMaxMemory());
max_allowed_footprint = GetMaxMemory();
}
max_allowed_footprint_ = max_allowed_footprint;
}
bool Heap::IsMovableObject(const mirror::Object* obj) const {
if (kMovingCollector) {
space::Space* space = FindContinuousSpaceFromObject(obj, true);
if (space != nullptr) {
// TODO: Check large object?
return space->CanMoveObjects();
}
}
return false;
}
void Heap::UpdateMaxNativeFootprint() {
size_t native_size = native_bytes_allocated_.LoadRelaxed();
// TODO: Tune the native heap utilization to be a value other than the java heap utilization.
size_t target_size = native_size / GetTargetHeapUtilization();
if (target_size > native_size + max_free_) {
target_size = native_size + max_free_;
} else if (target_size < native_size + min_free_) {
target_size = native_size + min_free_;
}
native_footprint_gc_watermark_ = std::min(growth_limit_, target_size);
}
collector::GarbageCollector* Heap::FindCollectorByGcType(collector::GcType gc_type) {
for (const auto& collector : garbage_collectors_) {
if (collector->GetCollectorType() == collector_type_ &&
collector->GetGcType() == gc_type) {
return collector;
}
}
return nullptr;
}
double Heap::HeapGrowthMultiplier() const {
// If we don't care about pause times we are background, so return 1.0.
if (!CareAboutPauseTimes() || IsLowMemoryMode()) {
return 1.0;
}
return foreground_heap_growth_multiplier_;
}
void Heap::GrowForUtilization(collector::GarbageCollector* collector_ran) {
// We know what our utilization is at this moment.
// This doesn't actually resize any memory. It just lets the heap grow more when necessary.
const uint64_t bytes_allocated = GetBytesAllocated();
last_gc_size_ = bytes_allocated;
last_gc_time_ns_ = NanoTime();
uint64_t target_size;
collector::GcType gc_type = collector_ran->GetGcType();
if (gc_type != collector::kGcTypeSticky) {
// Grow the heap for non sticky GC.
const float multiplier = HeapGrowthMultiplier(); // Use the multiplier to grow more for
// foreground.
intptr_t delta = bytes_allocated / GetTargetHeapUtilization() - bytes_allocated;
CHECK_GE(delta, 0);
target_size = bytes_allocated + delta * multiplier;
target_size = std::min(target_size,
bytes_allocated + static_cast<uint64_t>(max_free_ * multiplier));
target_size = std::max(target_size,
bytes_allocated + static_cast<uint64_t>(min_free_ * multiplier));
native_need_to_run_finalization_ = true;
next_gc_type_ = collector::kGcTypeSticky;
} else {
collector::GcType non_sticky_gc_type =
have_zygote_space_ ? collector::kGcTypePartial : collector::kGcTypeFull;
// Find what the next non sticky collector will be.
collector::GarbageCollector* non_sticky_collector = FindCollectorByGcType(non_sticky_gc_type);
// If the throughput of the current sticky GC >= throughput of the non sticky collector, then
// do another sticky collection next.
// We also check that the bytes allocated aren't over the footprint limit in order to prevent a
// pathological case where dead objects which aren't reclaimed by sticky could get accumulated
// if the sticky GC throughput always remained >= the full/partial throughput.
if (current_gc_iteration_.GetEstimatedThroughput() * kStickyGcThroughputAdjustment >=
non_sticky_collector->GetEstimatedMeanThroughput() &&
non_sticky_collector->NumberOfIterations() > 0 &&
bytes_allocated <= max_allowed_footprint_) {
next_gc_type_ = collector::kGcTypeSticky;
} else {
next_gc_type_ = non_sticky_gc_type;
}
// If we have freed enough memory, shrink the heap back down.
if (bytes_allocated + max_free_ < max_allowed_footprint_) {
target_size = bytes_allocated + max_free_;
} else {
target_size = std::max(bytes_allocated, static_cast<uint64_t>(max_allowed_footprint_));
}
}
if (!ignore_max_footprint_) {
SetIdealFootprint(target_size);
if (IsGcConcurrent()) {
// Calculate when to perform the next ConcurrentGC.
// Calculate the estimated GC duration.
const double gc_duration_seconds = NsToMs(current_gc_iteration_.GetDurationNs()) / 1000.0;
// Estimate how many remaining bytes we will have when we need to start the next GC.
size_t remaining_bytes = allocation_rate_ * gc_duration_seconds;
remaining_bytes = std::min(remaining_bytes, kMaxConcurrentRemainingBytes);
remaining_bytes = std::max(remaining_bytes, kMinConcurrentRemainingBytes);
if (UNLIKELY(remaining_bytes > max_allowed_footprint_)) {
// A never going to happen situation that from the estimated allocation rate we will exceed
// the applications entire footprint with the given estimated allocation rate. Schedule
// another GC nearly straight away.
remaining_bytes = kMinConcurrentRemainingBytes;
}
DCHECK_LE(remaining_bytes, max_allowed_footprint_);
DCHECK_LE(max_allowed_footprint_, GetMaxMemory());
// Start a concurrent GC when we get close to the estimated remaining bytes. When the
// allocation rate is very high, remaining_bytes could tell us that we should start a GC
// right away.
concurrent_start_bytes_ = std::max(max_allowed_footprint_ - remaining_bytes,
static_cast<size_t>(bytes_allocated));
}
}
}
void Heap::ClearGrowthLimit() {
growth_limit_ = capacity_;
for (const auto& space : continuous_spaces_) {
if (space->IsMallocSpace()) {
gc::space::MallocSpace* malloc_space = space->AsMallocSpace();
malloc_space->ClearGrowthLimit();
malloc_space->SetFootprintLimit(malloc_space->Capacity());
}
}
// This space isn't added for performance reasons.
if (main_space_backup_.get() != nullptr) {
main_space_backup_->ClearGrowthLimit();
main_space_backup_->SetFootprintLimit(main_space_backup_->Capacity());
}
}
void Heap::AddFinalizerReference(Thread* self, mirror::Object** object) {
ScopedObjectAccess soa(self);
ScopedLocalRef<jobject> arg(self->GetJniEnv(), soa.AddLocalReference<jobject>(*object));
jvalue args[1];
args[0].l = arg.get();
InvokeWithJValues(soa, nullptr, WellKnownClasses::java_lang_ref_FinalizerReference_add, args);
// Restore object in case it gets moved.
*object = soa.Decode<mirror::Object*>(arg.get());
}
void Heap::RequestConcurrentGCAndSaveObject(Thread* self, mirror::Object** obj) {
StackHandleScope<1> hs(self);
HandleWrapper<mirror::Object> wrapper(hs.NewHandleWrapper(obj));
RequestConcurrentGC(self);
}
void Heap::RequestConcurrentGC(Thread* self) {
// Make sure that we can do a concurrent GC.
Runtime* runtime = Runtime::Current();
if (runtime == nullptr || !runtime->IsFinishedStarting() || runtime->IsShuttingDown(self) ||
self->IsHandlingStackOverflow()) {
return;
}
JNIEnv* env = self->GetJniEnv();
DCHECK(WellKnownClasses::java_lang_Daemons != nullptr);
DCHECK(WellKnownClasses::java_lang_Daemons_requestGC != nullptr);
env->CallStaticVoidMethod(WellKnownClasses::java_lang_Daemons,
WellKnownClasses::java_lang_Daemons_requestGC);
CHECK(!env->ExceptionCheck());
}
void Heap::ConcurrentGC(Thread* self) {
if (Runtime::Current()->IsShuttingDown(self)) {
return;
}
// Wait for any GCs currently running to finish.
if (WaitForGcToComplete(kGcCauseBackground, self) == collector::kGcTypeNone) {
// If the we can't run the GC type we wanted to run, find the next appropriate one and try that
// instead. E.g. can't do partial, so do full instead.
if (CollectGarbageInternal(next_gc_type_, kGcCauseBackground, false) ==
collector::kGcTypeNone) {
for (collector::GcType gc_type : gc_plan_) {
// Attempt to run the collector, if we succeed, we are done.
if (gc_type > next_gc_type_ &&
CollectGarbageInternal(gc_type, kGcCauseBackground, false) != collector::kGcTypeNone) {
break;
}
}
}
}
}
void Heap::RequestCollectorTransition(CollectorType desired_collector_type, uint64_t delta_time) {
Thread* self = Thread::Current();
{
MutexLock mu(self, *heap_trim_request_lock_);
if (desired_collector_type_ == desired_collector_type) {
return;
}
heap_transition_or_trim_target_time_ =
std::max(heap_transition_or_trim_target_time_, NanoTime() + delta_time);
desired_collector_type_ = desired_collector_type;
}
SignalHeapTrimDaemon(self);
}
void Heap::RequestHeapTrim() {
// GC completed and now we must decide whether to request a heap trim (advising pages back to the
// kernel) or not. Issuing a request will also cause trimming of the libc heap. As a trim scans
// a space it will hold its lock and can become a cause of jank.
// Note, the large object space self trims and the Zygote space was trimmed and unchanging since
// forking.
// We don't have a good measure of how worthwhile a trim might be. We can't use the live bitmap
// because that only marks object heads, so a large array looks like lots of empty space. We
// don't just call dlmalloc all the time, because the cost of an _attempted_ trim is proportional
// to utilization (which is probably inversely proportional to how much benefit we can expect).
// We could try mincore(2) but that's only a measure of how many pages we haven't given away,
// not how much use we're making of those pages.
Thread* self = Thread::Current();
Runtime* runtime = Runtime::Current();
if (runtime == nullptr || !runtime->IsFinishedStarting() || runtime->IsShuttingDown(self) ||
runtime->IsZygote()) {
// Ignore the request if we are the zygote to prevent app launching lag due to sleep in heap
// trimmer daemon. b/17310019
// Heap trimming isn't supported without a Java runtime or Daemons (such as at dex2oat time)
// Also: we do not wish to start a heap trim if the runtime is shutting down (a racy check
// as we don't hold the lock while requesting the trim).
return;
}
{
MutexLock mu(self, *heap_trim_request_lock_);
if (last_trim_time_ + kHeapTrimWait >= NanoTime()) {
// We have done a heap trim in the last kHeapTrimWait nanosecs, don't request another one
// just yet.
return;
}
heap_trim_request_pending_ = true;
uint64_t current_time = NanoTime();
if (heap_transition_or_trim_target_time_ < current_time) {
heap_transition_or_trim_target_time_ = current_time + kHeapTrimWait;
}
}
// Notify the daemon thread which will actually do the heap trim.
SignalHeapTrimDaemon(self);
}
void Heap::SignalHeapTrimDaemon(Thread* self) {
JNIEnv* env = self->GetJniEnv();
DCHECK(WellKnownClasses::java_lang_Daemons != nullptr);
DCHECK(WellKnownClasses::java_lang_Daemons_requestHeapTrim != nullptr);
env->CallStaticVoidMethod(WellKnownClasses::java_lang_Daemons,
WellKnownClasses::java_lang_Daemons_requestHeapTrim);
CHECK(!env->ExceptionCheck());
}
void Heap::RevokeThreadLocalBuffers(Thread* thread) {
if (rosalloc_space_ != nullptr) {
rosalloc_space_->RevokeThreadLocalBuffers(thread);
}
if (bump_pointer_space_ != nullptr) {
bump_pointer_space_->RevokeThreadLocalBuffers(thread);
}
}
void Heap::RevokeRosAllocThreadLocalBuffers(Thread* thread) {
if (rosalloc_space_ != nullptr) {
rosalloc_space_->RevokeThreadLocalBuffers(thread);
}
}
void Heap::RevokeAllThreadLocalBuffers() {
if (rosalloc_space_ != nullptr) {
rosalloc_space_->RevokeAllThreadLocalBuffers();
}
if (bump_pointer_space_ != nullptr) {
bump_pointer_space_->RevokeAllThreadLocalBuffers();
}
}
bool Heap::IsGCRequestPending() const {
return concurrent_start_bytes_ != std::numeric_limits<size_t>::max();
}
void Heap::RunFinalization(JNIEnv* env) {
// Can't do this in WellKnownClasses::Init since System is not properly set up at that point.
if (WellKnownClasses::java_lang_System_runFinalization == nullptr) {
CHECK(WellKnownClasses::java_lang_System != nullptr);
WellKnownClasses::java_lang_System_runFinalization =
CacheMethod(env, WellKnownClasses::java_lang_System, true, "runFinalization", "()V");
CHECK(WellKnownClasses::java_lang_System_runFinalization != nullptr);
}
env->CallStaticVoidMethod(WellKnownClasses::java_lang_System,
WellKnownClasses::java_lang_System_runFinalization);
env->CallStaticVoidMethod(WellKnownClasses::java_lang_System,
WellKnownClasses::java_lang_System_runFinalization);
}
void Heap::RegisterNativeAllocation(JNIEnv* env, size_t bytes) {
Thread* self = ThreadForEnv(env);
if (native_need_to_run_finalization_) {
RunFinalization(env);
UpdateMaxNativeFootprint();
native_need_to_run_finalization_ = false;
}
// Total number of native bytes allocated.
size_t new_native_bytes_allocated = native_bytes_allocated_.FetchAndAddSequentiallyConsistent(bytes);
new_native_bytes_allocated += bytes;
if (new_native_bytes_allocated > native_footprint_gc_watermark_) {
collector::GcType gc_type = have_zygote_space_ ? collector::kGcTypePartial :
collector::kGcTypeFull;
// The second watermark is higher than the gc watermark. If you hit this it means you are
// allocating native objects faster than the GC can keep up with.
if (new_native_bytes_allocated > growth_limit_) {
if (WaitForGcToComplete(kGcCauseForNativeAlloc, self) != collector::kGcTypeNone) {
// Just finished a GC, attempt to run finalizers.
RunFinalization(env);
CHECK(!env->ExceptionCheck());
}
// If we still are over the watermark, attempt a GC for alloc and run finalizers.
if (new_native_bytes_allocated > growth_limit_) {
CollectGarbageInternal(gc_type, kGcCauseForNativeAlloc, false);
RunFinalization(env);
native_need_to_run_finalization_ = false;
CHECK(!env->ExceptionCheck());
}
// We have just run finalizers, update the native watermark since it is very likely that
// finalizers released native managed allocations.
UpdateMaxNativeFootprint();
} else if (!IsGCRequestPending()) {
if (IsGcConcurrent()) {
RequestConcurrentGC(self);
} else {
CollectGarbageInternal(gc_type, kGcCauseForNativeAlloc, false);
}
}
}
}
void Heap::RegisterNativeFree(JNIEnv* env, size_t bytes) {
size_t expected_size;
do {
expected_size = native_bytes_allocated_.LoadRelaxed();
if (UNLIKELY(bytes > expected_size)) {
ScopedObjectAccess soa(env);
env->ThrowNew(WellKnownClasses::java_lang_RuntimeException,
StringPrintf("Attempted to free %zd native bytes with only %zd native bytes "
"registered as allocated", bytes, expected_size).c_str());
break;
}
} while (!native_bytes_allocated_.CompareExchangeWeakRelaxed(expected_size,
expected_size - bytes));
}
size_t Heap::GetTotalMemory() const {
return std::max(max_allowed_footprint_, GetBytesAllocated());
}
void Heap::AddModUnionTable(accounting::ModUnionTable* mod_union_table) {
DCHECK(mod_union_table != nullptr);
mod_union_tables_.Put(mod_union_table->GetSpace(), mod_union_table);
}
void Heap::CheckPreconditionsForAllocObject(mirror::Class* c, size_t byte_count) {
CHECK(c == NULL || (c->IsClassClass() && byte_count >= sizeof(mirror::Class)) ||
(c->IsVariableSize() || c->GetObjectSize() == byte_count));
CHECK_GE(byte_count, sizeof(mirror::Object));
}
void Heap::AddRememberedSet(accounting::RememberedSet* remembered_set) {
CHECK(remembered_set != nullptr);
space::Space* space = remembered_set->GetSpace();
CHECK(space != nullptr);
CHECK(remembered_sets_.find(space) == remembered_sets_.end()) << space;
remembered_sets_.Put(space, remembered_set);
CHECK(remembered_sets_.find(space) != remembered_sets_.end()) << space;
}
void Heap::RemoveRememberedSet(space::Space* space) {
CHECK(space != nullptr);
auto it = remembered_sets_.find(space);
CHECK(it != remembered_sets_.end());
delete it->second;
remembered_sets_.erase(it);
CHECK(remembered_sets_.find(space) == remembered_sets_.end());
}
void Heap::ClearMarkedObjects() {
// Clear all of the spaces' mark bitmaps.
for (const auto& space : GetContinuousSpaces()) {
accounting::ContinuousSpaceBitmap* mark_bitmap = space->GetMarkBitmap();
if (space->GetLiveBitmap() != mark_bitmap) {
mark_bitmap->Clear();
}
}
// Clear the marked objects in the discontinous space object sets.
for (const auto& space : GetDiscontinuousSpaces()) {
space->GetMarkBitmap()->Clear();
}
}
} // namespace gc
} // namespace art