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android / platform / art / 0adc680c388913a63666797e907f87c4c6b0b4ea / . / runtime / gc / heap.cc
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/*
* 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 <vector>
#include <valgrind.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/space_bitmap-inl.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/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 "heap-inl.h"
#include "image.h"
#include "invoke_arg_array_builder.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 "object_utils.h"
#include "os.h"
#include "runtime.h"
#include "ScopedLocalRef.h"
#include "scoped_thread_state_change.h"
#include "sirt_ref.h"
#include "thread_list.h"
#include "UniquePtr.h"
#include "well_known_classes.h"
namespace art {
extern void SetQuickAllocEntryPointsAllocator(gc::AllocatorType allocator);
namespace gc {
static constexpr bool kGCALotMode = false;
static constexpr size_t kGcAlotInterval = KB;
// Minimum amount of remaining bytes before a concurrent GC is triggered.
static constexpr size_t kMinConcurrentRemainingBytes = 128 * KB;
Heap::Heap(size_t initial_size, size_t growth_limit, size_t min_free, size_t max_free,
double target_utilization, size_t capacity, const std::string& image_file_name,
CollectorType post_zygote_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)
: non_moving_space_(nullptr),
rosalloc_space_(nullptr),
dlmalloc_space_(nullptr),
concurrent_gc_(false),
collector_type_(kCollectorTypeNone),
post_zygote_collector_type_(post_zygote_collector_type),
background_collector_type_(background_collector_type),
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),
have_zygote_space_(false),
soft_reference_queue_(this),
weak_reference_queue_(this),
finalizer_reference_queue_(this),
phantom_reference_queue_(this),
cleared_references_(this),
is_gc_running_(false),
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_footprint_limit_(2 * 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),
gc_memory_overhead_(0),
verify_missing_card_marks_(false),
verify_system_weaks_(false),
verify_pre_gc_heap_(false),
verify_post_gc_heap_(false),
verify_mod_union_table_(false),
min_alloc_space_size_for_sticky_gc_(1112 * MB),
min_remaining_space_for_sticky_gc_(1 * MB),
last_trim_time_ms_(0),
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 ? kGcAlotInterval
: (kDesiredHeapVerification > kVerifyAllFast) ? KB : MB),
current_allocator_(kAllocatorTypeDlMalloc),
current_non_moving_allocator_(kAllocatorTypeNonMoving),
bump_pointer_space_(nullptr),
temp_space_(nullptr),
reference_referent_offset_(0),
reference_queue_offset_(0),
reference_queueNext_offset_(0),
reference_pendingNext_offset_(0),
finalizer_reference_zombie_offset_(0),
min_free_(min_free),
max_free_(max_free),
target_utilization_(target_utilization),
total_wait_time_(0),
total_allocation_time_(0),
verify_object_mode_(kHeapVerificationNotPermitted),
gc_disable_count_(0),
running_on_valgrind_(RUNNING_ON_VALGRIND),
use_tlab_(use_tlab) {
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.
if (!Runtime::Current()->IsZygote() || !kMovingCollector) {
ChangeCollector(post_zygote_collector_type_);
} else {
// We are the zygote, use bump pointer allocation + semi space collector.
ChangeCollector(kCollectorTypeSS);
}
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()) {
space::ImageSpace* image_space = space::ImageSpace::Create(image_file_name.c_str());
CHECK(image_space != nullptr) << "Failed to create space for " << image_file_name;
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());
if (oat_file_end_addr > requested_alloc_space_begin) {
requested_alloc_space_begin = AlignUp(oat_file_end_addr, kPageSize);
}
}
const char* name = Runtime::Current()->IsZygote() ? "zygote space" : "alloc space";
space::MallocSpace* malloc_space;
if (kUseRosAlloc) {
malloc_space = space::RosAllocSpace::Create(name, initial_size, growth_limit, capacity,
requested_alloc_space_begin, low_memory_mode_);
CHECK(malloc_space != nullptr) << "Failed to create rosalloc space";
} else {
malloc_space = space::DlMallocSpace::Create(name, initial_size, growth_limit, capacity,
requested_alloc_space_begin);
CHECK(malloc_space != nullptr) << "Failed to create dlmalloc space";
}
if (kMovingCollector) {
// TODO: Place bump-pointer spaces somewhere to minimize size of card table.
// TODO: Having 3+ spaces as big as the large heap size can cause virtual memory fragmentation
// issues.
const size_t bump_pointer_space_size = std::min(malloc_space->Capacity(), 128 * MB);
bump_pointer_space_ = space::BumpPointerSpace::Create("Bump pointer space",
bump_pointer_space_size, nullptr);
CHECK(bump_pointer_space_ != nullptr) << "Failed to create bump pointer space";
AddSpace(bump_pointer_space_);
temp_space_ = space::BumpPointerSpace::Create("Bump pointer space 2", bump_pointer_space_size,
nullptr);
CHECK(temp_space_ != nullptr) << "Failed to create bump pointer space";
AddSpace(temp_space_);
}
non_moving_space_ = malloc_space;
malloc_space->SetFootprintLimit(malloc_space->Capacity());
AddSpace(malloc_space);
// Allocate the large object space.
constexpr bool kUseFreeListSpaceForLOS = false;
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;
// 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::ModUnionTableCardCache("Image mod-union table", this, GetImageSpace());
CHECK(mod_union_table != nullptr) << "Failed to create image mod-union table";
AddModUnionTable(mod_union_table);
// TODO: Count objects in the image space here.
num_bytes_allocated_ = 0;
// Default mark stack size in bytes.
static const size_t default_mark_stack_size = 64 * KB;
mark_stack_.reset(accounting::ObjectStack::Create("mark stack", default_mark_stack_size));
allocation_stack_.reset(accounting::ObjectStack::Create("allocation stack",
max_allocation_stack_size_));
live_stack_.reset(accounting::ObjectStack::Create("live stack",
max_allocation_stack_size_));
// 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_));
last_gc_time_ns_ = NanoTime();
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.
semi_space_collector_ = new collector::SemiSpace(this);
garbage_collectors_.push_back(semi_space_collector_);
}
if (running_on_valgrind_) {
Runtime::Current()->GetInstrumentation()->InstrumentQuickAllocEntryPoints();
}
if (VLOG_IS_ON(heap) || VLOG_IS_ON(startup)) {
LOG(INFO) << "Heap() exiting";
}
}
void Heap::ChangeAllocator(AllocatorType allocator) {
// These two allocators are only used internally and don't have any entrypoints.
DCHECK_NE(allocator, kAllocatorTypeLOS);
DCHECK_NE(allocator, kAllocatorTypeNonMoving);
if (current_allocator_ != allocator) {
current_allocator_ = allocator;
SetQuickAllocEntryPointsAllocator(current_allocator_);
Runtime::Current()->GetInstrumentation()->ResetQuickAllocEntryPoints();
}
}
bool Heap::IsCompilingBoot() const {
for (const auto& space : continuous_spaces_) {
if (space->IsImageSpace()) {
return false;
} else if (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::IncrementDisableGC(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_);
WaitForGcToCompleteLocked(self);
++gc_disable_count_;
}
void Heap::DecrementDisableGC(Thread* self) {
MutexLock mu(self, *gc_complete_lock_);
CHECK_GE(gc_disable_count_, 0U);
--gc_disable_count_;
}
void Heap::UpdateProcessState(ProcessState process_state) {
if (process_state_ != process_state) {
process_state_ = process_state;
if (process_state_ == kProcessStateJankPerceptible) {
TransitionCollector(post_zygote_collector_type_);
} else {
TransitionCollector(background_collector_type_);
}
} else {
CollectGarbageInternal(collector::kGcTypeFull, kGcCauseBackground, false);
}
}
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(ObjectVisitorCallback 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;
callback(obj, arg);
}
GetLiveBitmap()->Walk(callback, arg);
self->EndAssertNoThreadSuspension(old_cause);
}
void Heap::MarkAllocStackAsLive(accounting::ObjectStack* stack) {
space::ContinuousSpace* space1 = rosalloc_space_ != nullptr ? rosalloc_space_ : non_moving_space_;
space::ContinuousSpace* space2 = dlmalloc_space_ != nullptr ? dlmalloc_space_ : non_moving_space_;
// This is just logic to handle a case of either not having a rosalloc or dlmalloc space.
// TODO: Generalize this to n bitmaps?
if (space1 == nullptr) {
DCHECK(space2 != nullptr);
space1 = space2;
}
if (space2 == nullptr) {
DCHECK(space1 != nullptr);
space2 = space1;
}
MarkAllocStack(space1->GetLiveBitmap(), space2->GetLiveBitmap(),
large_object_space_->GetLiveObjects(), stack);
}
void Heap::DeleteThreadPool() {
thread_pool_.reset(nullptr);
}
void Heap::AddSpace(space::Space* space, bool set_as_default) {
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::SpaceBitmap* live_bitmap = continuous_space->GetLiveBitmap();
accounting::SpaceBitmap* mark_bitmap = continuous_space->GetMarkBitmap();
if (live_bitmap != nullptr) {
DCHECK(mark_bitmap != nullptr);
live_bitmap_->AddContinuousSpaceBitmap(live_bitmap);
mark_bitmap_->AddContinuousSpaceBitmap(mark_bitmap);
}
continuous_spaces_.push_back(continuous_space);
if (set_as_default) {
if (continuous_space->IsDlMallocSpace()) {
dlmalloc_space_ = continuous_space->AsDlMallocSpace();
} else if (continuous_space->IsRosAllocSpace()) {
rosalloc_space_ = continuous_space->AsRosAllocSpace();
}
}
// 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 {
DCHECK(space->IsDiscontinuousSpace());
space::DiscontinuousSpace* discontinuous_space = space->AsDiscontinuousSpace();
DCHECK(discontinuous_space->GetLiveObjects() != nullptr);
live_bitmap_->AddDiscontinuousObjectSet(discontinuous_space->GetLiveObjects());
DCHECK(discontinuous_space->GetMarkObjects() != nullptr);
mark_bitmap_->AddDiscontinuousObjectSet(discontinuous_space->GetMarkObjects());
discontinuous_spaces_.push_back(discontinuous_space);
}
if (space->IsAllocSpace()) {
alloc_spaces_.push_back(space->AsAllocSpace());
}
}
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::SpaceBitmap* live_bitmap = continuous_space->GetLiveBitmap();
accounting::SpaceBitmap* 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);
if (continuous_space == dlmalloc_space_) {
dlmalloc_space_ = nullptr;
} else if (continuous_space == rosalloc_space_) {
rosalloc_space_ = nullptr;
}
} else {
DCHECK(space->IsDiscontinuousSpace());
space::DiscontinuousSpace* discontinuous_space = space->AsDiscontinuousSpace();
DCHECK(discontinuous_space->GetLiveObjects() != nullptr);
live_bitmap_->RemoveDiscontinuousObjectSet(discontinuous_space->GetLiveObjects());
DCHECK(discontinuous_space->GetMarkObjects() != nullptr);
mark_bitmap_->RemoveDiscontinuousObjectSet(discontinuous_space->GetMarkObjects());
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::RegisterGCAllocation(size_t bytes) {
if (this != nullptr) {
gc_memory_overhead_.FetchAndAdd(bytes);
}
}
void Heap::RegisterGCDeAllocation(size_t bytes) {
if (this != nullptr) {
gc_memory_overhead_.FetchAndSub(bytes);
}
}
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 (const auto& collector : garbage_collectors_) {
CumulativeLogger& logger = collector->GetCumulativeTimings();
if (logger.GetTotalNs() != 0) {
os << Dumpable<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;
collector->GetPauseHistogram().CreateHistogram(&cumulative_data);
collector->GetPauseHistogram().PrintConfidenceIntervals(os, 0.99, cumulative_data);
os << collector->GetName() << " total time: " << PrettyDuration(total_ns) << "\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;
}
}
uint64_t allocation_time = static_cast<uint64_t>(total_allocation_time_) * 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";
}
size_t total_objects_allocated = GetObjectsAllocatedEver();
os << "Total number of allocations: " << total_objects_allocated << "\n";
size_t total_bytes_allocated = GetBytesAllocatedEver();
os << "Total bytes allocated " << PrettySize(total_bytes_allocated) << "\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";
os << "Approximate GC data structures memory overhead: " << gc_memory_overhead_;
}
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_);
STLDeleteElements(&continuous_spaces_);
STLDeleteElements(&discontinuous_spaces_);
delete gc_complete_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);
}
struct SoftReferenceArgs {
RootVisitor* is_marked_callback_;
RootVisitor* recursive_mark_callback_;
void* arg_;
};
mirror::Object* Heap::PreserveSoftReferenceCallback(mirror::Object* obj, void* arg) {
SoftReferenceArgs* args = reinterpret_cast<SoftReferenceArgs*>(arg);
// TODO: Not preserve all soft references.
return args->recursive_mark_callback_(obj, args->arg_);
}
// Process reference class instances and schedule finalizations.
void Heap::ProcessReferences(TimingLogger& timings, bool clear_soft,
RootVisitor* is_marked_callback,
RootVisitor* recursive_mark_object_callback, void* arg) {
// Unless we are in the zygote or required to clear soft references with white references,
// preserve some white referents.
if (!clear_soft && !Runtime::Current()->IsZygote()) {
SoftReferenceArgs soft_reference_args;
soft_reference_args.is_marked_callback_ = is_marked_callback;
soft_reference_args.recursive_mark_callback_ = recursive_mark_object_callback;
soft_reference_args.arg_ = arg;
soft_reference_queue_.PreserveSomeSoftReferences(&PreserveSoftReferenceCallback,
&soft_reference_args);
}
timings.StartSplit("ProcessReferences");
// Clear all remaining soft and weak references with white referents.
soft_reference_queue_.ClearWhiteReferences(cleared_references_, is_marked_callback, arg);
weak_reference_queue_.ClearWhiteReferences(cleared_references_, is_marked_callback, arg);
timings.EndSplit();
// Preserve all white objects with finalize methods and schedule them for finalization.
timings.StartSplit("EnqueueFinalizerReferences");
finalizer_reference_queue_.EnqueueFinalizerReferences(cleared_references_, is_marked_callback,
recursive_mark_object_callback, arg);
timings.EndSplit();
timings.StartSplit("ProcessReferences");
// Clear all f-reachable soft and weak references with white referents.
soft_reference_queue_.ClearWhiteReferences(cleared_references_, is_marked_callback, arg);
weak_reference_queue_.ClearWhiteReferences(cleared_references_, is_marked_callback, arg);
// Clear all phantom references with white referents.
phantom_reference_queue_.ClearWhiteReferences(cleared_references_, is_marked_callback, arg);
// At this point all reference queues other than the cleared references should be empty.
DCHECK(soft_reference_queue_.IsEmpty());
DCHECK(weak_reference_queue_.IsEmpty());
DCHECK(finalizer_reference_queue_.IsEmpty());
DCHECK(phantom_reference_queue_.IsEmpty());
timings.EndSplit();
}
bool Heap::IsEnqueued(mirror::Object* ref) const {
// Since the references are stored as cyclic lists it means that once enqueued, the pending next
// will always be non-null.
return ref->GetFieldObject<mirror::Object*>(GetReferencePendingNextOffset(), false) != nullptr;
}
bool Heap::IsEnqueuable(const mirror::Object* ref) const {
DCHECK(ref != nullptr);
const mirror::Object* queue =
ref->GetFieldObject<mirror::Object*>(GetReferenceQueueOffset(), false);
const mirror::Object* queue_next =
ref->GetFieldObject<mirror::Object*>(GetReferenceQueueNextOffset(), false);
return queue != nullptr && queue_next == nullptr;
}
// Process the "referent" field in a java.lang.ref.Reference. If the referent has not yet been
// marked, put it on the appropriate list in the heap for later processing.
void Heap::DelayReferenceReferent(mirror::Class* klass, mirror::Object* obj,
RootVisitor mark_visitor, void* arg) {
DCHECK(klass != nullptr);
DCHECK(klass->IsReferenceClass());
DCHECK(obj != nullptr);
mirror::Object* referent = GetReferenceReferent(obj);
if (referent != nullptr) {
mirror::Object* forward_address = mark_visitor(referent, arg);
// Null means that the object is not currently marked.
if (forward_address == nullptr) {
Thread* self = Thread::Current();
// TODO: Remove these locks, and use atomic stacks for storing references?
// We need to check that the references haven't already been enqueued since we can end up
// scanning the same reference multiple times due to dirty cards.
if (klass->IsSoftReferenceClass()) {
soft_reference_queue_.AtomicEnqueueIfNotEnqueued(self, obj);
} else if (klass->IsWeakReferenceClass()) {
weak_reference_queue_.AtomicEnqueueIfNotEnqueued(self, obj);
} else if (klass->IsFinalizerReferenceClass()) {
finalizer_reference_queue_.AtomicEnqueueIfNotEnqueued(self, obj);
} else if (klass->IsPhantomReferenceClass()) {
phantom_reference_queue_.AtomicEnqueueIfNotEnqueued(self, obj);
} else {
LOG(FATAL) << "Invalid reference type " << PrettyClass(klass) << " " << std::hex
<< klass->GetAccessFlags();
}
} else if (referent != forward_address) {
// Referent is already marked and we need to update it.
SetReferenceReferent(obj, forward_address);
}
}
}
space::ImageSpace* Heap::GetImageSpace() const {
for (const auto& space : continuous_spaces_) {
if (space->IsImageSpace()) {
return space->AsImageSpace();
}
}
return NULL;
}
static void MSpaceChunkCallback(void* start, void* end, size_t used_bytes, void* arg) {
size_t chunk_size = reinterpret_cast<uint8_t*>(end) - reinterpret_cast<uint8_t*>(start);
if (used_bytes < chunk_size) {
size_t chunk_free_bytes = chunk_size - used_bytes;
size_t& max_contiguous_allocation = *reinterpret_cast<size_t*>(arg);
max_contiguous_allocation = std::max(max_contiguous_allocation, chunk_free_bytes);
}
}
void Heap::ThrowOutOfMemoryError(Thread* self, size_t byte_count, bool large_object_allocation) {
std::ostringstream oss;
int64_t total_bytes_free = GetFreeMemory();
oss << "Failed to allocate a " << byte_count << " byte allocation with " << total_bytes_free
<< " free bytes";
// If the allocation failed due to fragmentation, print out the largest continuous allocation.
if (!large_object_allocation && total_bytes_free >= byte_count) {
size_t max_contiguous_allocation = 0;
for (const auto& space : continuous_spaces_) {
if (space->IsMallocSpace()) {
// To allow the Walk/InspectAll() to exclusively-lock the mutator
// lock, temporarily release the shared access to the mutator
// lock here by transitioning to the suspended state.
Locks::mutator_lock_->AssertSharedHeld(self);
self->TransitionFromRunnableToSuspended(kSuspended);
space->AsMallocSpace()->Walk(MSpaceChunkCallback, &max_contiguous_allocation);
self->TransitionFromSuspendedToRunnable();
Locks::mutator_lock_->AssertSharedHeld(self);
}
}
oss << "; failed due to fragmentation (largest possible contiguous allocation "
<< max_contiguous_allocation << " bytes)";
}
self->ThrowOutOfMemoryError(oss.str().c_str());
}
void Heap::Trim() {
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() && !space->IsZygoteSpace()) {
gc::space::MallocSpace* alloc_space = space->AsMallocSpace();
total_alloc_space_size += alloc_space->Size();
managed_reclaimed += alloc_space->Trim();
}
}
total_alloc_space_allocated = GetBytesAllocated() - large_object_space_->GetBytesAllocated() -
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();
// Trim the native heap.
dlmalloc_trim(0);
size_t native_reclaimed = 0;
dlmalloc_inspect_all(DlmallocMadviseCallback, &native_reclaimed);
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) && IsHeapAddress(obj);
}
bool Heap::IsHeapAddress(const mirror::Object* obj) const {
if (kMovingCollector && bump_pointer_space_->HasAddress(obj)) {
return true;
}
// TODO: This probably doesn't work for large objects.
return FindSpaceFromObject(obj, true) != nullptr;
}
bool Heap::IsLiveObjectLocked(const mirror::Object* obj, bool search_allocation_stack,
bool search_live_stack, bool sorted) {
// Locks::heap_bitmap_lock_->AssertReaderHeld(Thread::Current());
if (obj == nullptr || UNLIKELY(!IsAligned<kObjectAlignment>(obj))) {
return false;
}
space::ContinuousSpace* c_space = FindContinuousSpaceFromObject(obj, true);
space::DiscontinuousSpace* d_space = NULL;
if (c_space != NULL) {
if (c_space->GetLiveBitmap()->Test(obj)) {
return true;
}
} else if (bump_pointer_space_->Contains(obj) || temp_space_->Contains(obj)) {
return true;
} else {
d_space = FindDiscontinuousSpaceFromObject(obj, true);
if (d_space != NULL) {
if (d_space->GetLiveObjects()->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(const_cast<mirror::Object*>(obj))) {
return true;
}
} else if (allocation_stack_->Contains(const_cast<mirror::Object*>(obj))) {
return true;
}
}
if (search_live_stack) {
if (sorted) {
if (live_stack_->ContainsSorted(const_cast<mirror::Object*>(obj))) {
return true;
}
} else if (live_stack_->Contains(const_cast<mirror::Object*>(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 != NULL) {
if (c_space->GetLiveBitmap()->Test(obj)) {
return true;
}
} else {
d_space = FindDiscontinuousSpaceFromObject(obj, true);
if (d_space != NULL && d_space->GetLiveObjects()->Test(obj)) {
return true;
}
}
return false;
}
void Heap::VerifyObjectImpl(const mirror::Object* obj) {
if (Thread::Current() == NULL ||
Runtime::Current()->GetThreadList()->GetLockOwner() == Thread::Current()->GetTid()) {
return;
}
VerifyObjectBody(obj);
}
void Heap::DumpSpaces(std::ostream& stream) {
for (const auto& space : continuous_spaces_) {
accounting::SpaceBitmap* live_bitmap = space->GetLiveBitmap();
accounting::SpaceBitmap* 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(const mirror::Object* obj) {
CHECK(IsAligned<kObjectAlignment>(obj)) << "Object isn't aligned: " << obj;
// Ignore early dawn of the universe verifications.
if (UNLIKELY(static_cast<size_t>(num_bytes_allocated_.Load()) < 10 * KB)) {
return;
}
const byte* raw_addr = reinterpret_cast<const byte*>(obj) +
mirror::Object::ClassOffset().Int32Value();
const mirror::Class* c = *reinterpret_cast<mirror::Class* const *>(raw_addr);
if (UNLIKELY(c == NULL)) {
LOG(FATAL) << "Null class in object: " << obj;
} else if (UNLIKELY(!IsAligned<kObjectAlignment>(c))) {
LOG(FATAL) << "Class isn't aligned: " << c << " in object: " << obj;
}
// Check obj.getClass().getClass() == obj.getClass().getClass().getClass()
// Note: we don't use the accessors here as they have internal sanity checks
// that we don't want to run
raw_addr = reinterpret_cast<const byte*>(c) + mirror::Object::ClassOffset().Int32Value();
const mirror::Class* c_c = *reinterpret_cast<mirror::Class* const *>(raw_addr);
raw_addr = reinterpret_cast<const byte*>(c_c) + mirror::Object::ClassOffset().Int32Value();
const mirror::Class* c_c_c = *reinterpret_cast<mirror::Class* const *>(raw_addr);
CHECK_EQ(c_c, c_c_c);
if (verify_object_mode_ > kVerifyAllFast) {
// TODO: the bitmap tests below are racy if VerifyObjectBody is called without the
// heap_bitmap_lock_.
if (!IsLiveObjectLocked(obj)) {
DumpSpaces();
LOG(FATAL) << "Object is dead: " << obj;
}
if (!IsLiveObjectLocked(c)) {
LOG(FATAL) << "Class of object is dead: " << c << " in object: " << obj;
}
}
}
void Heap::VerificationCallback(mirror::Object* obj, void* arg) {
DCHECK(obj != NULL);
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(int64_t freed_objects, int64_t freed_bytes) {
DCHECK_LE(freed_bytes, num_bytes_allocated_.Load());
num_bytes_allocated_.FetchAndSub(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;
}
}
mirror::Object* Heap::AllocateInternalWithGc(Thread* self, AllocatorType allocator,
size_t alloc_size, size_t* bytes_allocated,
mirror::Class** klass) {
mirror::Object* ptr = nullptr;
bool was_default_allocator = allocator == GetCurrentAllocator();
DCHECK(klass != nullptr);
SirtRef<mirror::Class> sirt_klass(self, *klass);
// The allocation failed. If the GC is running, block until it completes, and then retry the
// allocation.
collector::GcType last_gc = WaitForGcToComplete(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()) {
*klass = sirt_klass.get();
return nullptr;
}
// A GC was in progress and we blocked, retry allocation now that memory has been freed.
ptr = TryToAllocate<true, false>(self, allocator, alloc_size, bytes_allocated);
}
// Loop through our different Gc types and try to Gc until we get enough free memory.
for (collector::GcType gc_type : gc_plan_) {
if (ptr != nullptr) {
break;
}
// Attempt to run the collector, if we succeed, re-try the allocation.
bool gc_ran =
CollectGarbageInternal(gc_type, kGcCauseForAlloc, false) != collector::kGcTypeNone;
if (was_default_allocator && allocator != GetCurrentAllocator()) {
*klass = sirt_klass.get();
return nullptr;
}
if (gc_ran) {
// Did we free sufficient memory for the allocation to succeed?
ptr = TryToAllocate<true, false>(self, allocator, alloc_size, bytes_allocated);
}
}
// Allocations have failed after GCs; this is an exceptional state.
if (ptr == nullptr) {
// Try harder, growing the heap if necessary.
ptr = TryToAllocate<true, true>(self, allocator, alloc_size, bytes_allocated);
}
if (ptr == nullptr) {
// 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()) {
*klass = sirt_klass.get();
return nullptr;
}
ptr = TryToAllocate<true, true>(self, allocator, alloc_size, bytes_allocated);
if (ptr == nullptr) {
ThrowOutOfMemoryError(self, alloc_size, false);
}
}
*klass = sirt_klass.get();
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;
}
size_t Heap::GetObjectsAllocatedEver() const {
return GetObjectsFreedEver() + GetObjectsAllocated();
}
size_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) {
}
void operator()(const mirror::Object* o) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
for (size_t i = 0; i < classes_.size(); ++i) {
const mirror::Class* instance_class = o->GetClass();
if (use_is_assignable_from_) {
if (instance_class != NULL && classes_[i]->IsAssignableFrom(instance_class)) {
++counts_[i];
}
} else {
if (instance_class == classes_[i]) {
++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) {
// We only want reachable instances, so do a GC. This also ensures that the alloc stack
// is empty, so the live bitmap is the only place we need to look.
Thread* self = Thread::Current();
self->TransitionFromRunnableToSuspended(kNative);
CollectGarbage(false);
self->TransitionFromSuspendedToRunnable();
InstanceCounter counter(classes, use_is_assignable_from, counts);
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
GetLiveBitmap()->Visit(counter);
}
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) {
}
void operator()(const mirror::Object* o) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
const mirror::Class* instance_class = o->GetClass();
if (instance_class == class_) {
if (max_count_ == 0 || instances_.size() < max_count_) {
instances_.push_back(const_cast<mirror::Object*>(o));
}
}
}
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) {
// We only want reachable instances, so do a GC. This also ensures that the alloc stack
// is empty, so the live bitmap is the only place we need to look.
Thread* self = Thread::Current();
self->TransitionFromRunnableToSuspended(kNative);
CollectGarbage(false);
self->TransitionFromSuspendedToRunnable();
InstanceCollector collector(c, max_count, instances);
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
GetLiveBitmap()->Visit(collector);
}
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) {
}
// For bitmap Visit.
// TODO: Fix lock analysis to not use NO_THREAD_SAFETY_ANALYSIS, requires support for
// annotalysis on visitors.
void operator()(const mirror::Object* o) const NO_THREAD_SAFETY_ANALYSIS {
collector::MarkSweep::VisitObjectReferences(const_cast<mirror::Object*>(o), *this, true);
}
// For MarkSweep::VisitObjectReferences.
void operator()(mirror::Object* referrer, mirror::Object* object,
const MemberOffset&, bool) const {
if (object == object_ && (max_count_ == 0 || referring_objects_.size() < max_count_)) {
referring_objects_.push_back(referrer);
}
}
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) {
// We only want reachable instances, so do a GC. This also ensures that the alloc stack
// is empty, so the live bitmap is the only place we need to look.
Thread* self = Thread::Current();
self->TransitionFromRunnableToSuspended(kNative);
CollectGarbage(false);
self->TransitionFromSuspendedToRunnable();
ReferringObjectsFinder finder(o, max_count, referring_objects);
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
GetLiveBitmap()->Visit(finder);
}
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);
}
void Heap::TransitionCollector(CollectorType collector_type) {
if (collector_type == collector_type_) {
return;
}
uint64_t start_time = NanoTime();
int32_t before_size = GetTotalMemory();
int32_t before_allocated = num_bytes_allocated_.Load();
ThreadList* tl = Runtime::Current()->GetThreadList();
Thread* 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 gc_disable_count_, this
// rarely occurs however).
while (!StartGC(self)) {
usleep(100);
}
tl->SuspendAll();
switch (collector_type) {
case kCollectorTypeSS: {
mprotect(temp_space_->Begin(), temp_space_->Capacity(), PROT_READ | PROT_WRITE);
space::MallocSpace* main_space;
if (rosalloc_space_ != nullptr) {
DCHECK(kUseRosAlloc);
main_space = rosalloc_space_;
} else {
DCHECK(dlmalloc_space_ != nullptr);
main_space = dlmalloc_space_;
}
Compact(temp_space_, main_space);
DCHECK(allocator_mem_map_.get() == nullptr);
allocator_mem_map_.reset(main_space->ReleaseMemMap());
madvise(main_space->Begin(), main_space->Size(), MADV_DONTNEED);
RemoveSpace(main_space);
break;
}
case kCollectorTypeMS:
// Fall through.
case kCollectorTypeCMS: {
if (collector_type_ == kCollectorTypeSS) {
// TODO: Use mem-map from temp space?
MemMap* mem_map = allocator_mem_map_.release();
CHECK(mem_map != nullptr);
size_t initial_size = kDefaultInitialSize;
mprotect(mem_map->Begin(), initial_size, PROT_READ | PROT_WRITE);
space::MallocSpace* malloc_space;
if (kUseRosAlloc) {
malloc_space =
space::RosAllocSpace::CreateFromMemMap(mem_map, "alloc space", kPageSize,
initial_size, mem_map->Size(),
mem_map->Size(), low_memory_mode_);
} else {
malloc_space =
space::DlMallocSpace::CreateFromMemMap(mem_map, "alloc space", kPageSize,
initial_size, mem_map->Size(),
mem_map->Size());
}
malloc_space->SetFootprintLimit(malloc_space->Capacity());
AddSpace(malloc_space);
Compact(malloc_space, bump_pointer_space_);
}
break;
}
default: {
LOG(FATAL) << "Attempted to transition to invalid collector type";
break;
}
}
ChangeCollector(collector_type);
tl->ResumeAll();
// Can't call into java code with all threads suspended.
EnqueueClearedReferences();
uint64_t duration = NanoTime() - start_time;
GrowForUtilization(collector::kGcTypeFull, duration);
FinishGC(self, collector::kGcTypeFull);
int32_t after_size = GetTotalMemory();
int32_t delta_size = before_size - after_size;
int32_t after_allocated = num_bytes_allocated_.Load();
int32_t delta_allocated = before_allocated - after_allocated;
const std::string saved_bytes_str =
delta_size < 0 ? "-" + PrettySize(-delta_size) : PrettySize(delta_size);
LOG(INFO) << "Heap transition to " << process_state_ << " took "
<< PrettyDuration(duration) << " " << PrettySize(before_size) << "->"
<< PrettySize(after_size) << " from " << PrettySize(delta_allocated) << " to "
<< PrettySize(delta_size) << " saved";
}
void Heap::ChangeCollector(CollectorType collector_type) {
// TODO: Only do this with all mutators suspended to avoid races.
if (collector_type != collector_type_) {
collector_type_ = collector_type;
gc_plan_.clear();
switch (collector_type_) {
case kCollectorTypeSS: {
concurrent_gc_ = false;
gc_plan_.push_back(collector::kGcTypeFull);
if (use_tlab_) {
ChangeAllocator(kAllocatorTypeTLAB);
} else {
ChangeAllocator(kAllocatorTypeBumpPointer);
}
break;
}
case kCollectorTypeMS: {
concurrent_gc_ = false;
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: {
concurrent_gc_ = true;
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 (concurrent_gc_) {
concurrent_start_bytes_ =
std::max(max_allowed_footprint_, kMinConcurrentRemainingBytes) - kMinConcurrentRemainingBytes;
} else {
concurrent_start_bytes_ = std::numeric_limits<size_t>::max();
}
}
}
static void MarkInBitmapCallback(mirror::Object* obj, void* arg) {
reinterpret_cast<accounting::SpaceBitmap*>(arg)->Set(obj);
}
void Heap::PreZygoteFork() {
static Mutex zygote_creation_lock_("zygote creation lock", kZygoteCreationLock);
Thread* self = Thread::Current();
MutexLock mu(self, zygote_creation_lock_);
// Try to see if we have any Zygote spaces.
if (have_zygote_space_) {
return;
}
VLOG(heap) << "Starting PreZygoteFork";
CollectGarbageInternal(collector::kGcTypeFull, kGcCauseBackground, false);
// Trim the pages at the end of the non moving space.
non_moving_space_->Trim();
non_moving_space_->GetMemMap()->Protect(PROT_READ | PROT_WRITE);
// Change the collector to the post zygote one.
ChangeCollector(post_zygote_collector_type_);
// TODO: Delete bump_pointer_space_ and temp_pointer_space_?
if (semi_space_collector_ != nullptr) {
// 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.
temp_space_->GetMemMap()->Protect(PROT_READ | PROT_WRITE);
Compact(&target_space, bump_pointer_space_);
CHECK(temp_space_->IsEmpty());
total_objects_freed_ever_ += semi_space_collector_->GetFreedObjects();
total_bytes_freed_ever_ += semi_space_collector_->GetFreedBytes();
// Update the end and write out image.
non_moving_space_->SetEnd(target_space.End());
non_moving_space_->SetLimit(target_space.Limit());
accounting::SpaceBitmap* bitmap = non_moving_space_->GetLiveBitmap();
// Record the allocations in the bitmap.
VLOG(heap) << "Recording zygote allocations";
target_space.Walk(MarkInBitmapCallback, bitmap);
}
// Turn the current alloc space into a zygote space and obtain the new alloc space composed of
// the remaining available heap memory.
space::MallocSpace* zygote_space = non_moving_space_;
non_moving_space_ = non_moving_space_->CreateZygoteSpace("alloc space", low_memory_mode_);
if (non_moving_space_->IsRosAllocSpace()) {
rosalloc_space_ = non_moving_space_->AsRosAllocSpace();
} else if (non_moving_space_->IsDlMallocSpace()) {
dlmalloc_space_ = non_moving_space_->AsDlMallocSpace();
}
// Can't use RosAlloc for non moving space due to thread local buffers.
non_moving_space_->SetFootprintLimit(non_moving_space_->Capacity());
// Change the GC retention policy of the zygote space to only collect when full.
zygote_space->SetGcRetentionPolicy(space::kGcRetentionPolicyFullCollect);
AddSpace(non_moving_space_);
have_zygote_space_ = true;
zygote_space->InvalidateAllocator();
// 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);
// Reset the cumulative loggers since we now have a few additional timing phases.
for (const auto& collector : garbage_collectors_) {
collector->ResetCumulativeStatistics();
}
// TODO: Not limited space for non-movable objects?
space::MallocSpace* new_non_moving_space
= space::DlMallocSpace::Create("Non moving dlmalloc space", 2 * MB, 64 * MB, 64 * MB,
nullptr);
AddSpace(new_non_moving_space, false);
CHECK(new_non_moving_space != nullptr) << "Failed to create new non-moving space";
new_non_moving_space->SetFootprintLimit(new_non_moving_space->Capacity());
non_moving_space_ = new_non_moving_space;
}
void Heap::FlushAllocStack() {
MarkAllocStackAsLive(allocation_stack_.get());
allocation_stack_->Reset();
}
void Heap::MarkAllocStack(accounting::SpaceBitmap* bitmap1,
accounting::SpaceBitmap* bitmap2,
accounting::SpaceSetMap* 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;
DCHECK(obj != nullptr);
if (bitmap1->HasAddress(obj)) {
bitmap1->Set(obj);
} else if (bitmap2->HasAddress(obj)) {
bitmap2->Set(obj);
} else {
large_objects->Set(obj);
}
}
}
const char* PrettyCause(GcCause cause) {
switch (cause) {
case kGcCauseForAlloc: return "Alloc";
case kGcCauseBackground: return "Background";
case kGcCauseExplicit: return "Explicit";
default:
LOG(FATAL) << "Unreachable";
}
return "";
}
void Heap::SwapSemiSpaces() {
// Swap the spaces so we allocate into the space which we just evacuated.
std::swap(bump_pointer_space_, temp_space_);
}
void Heap::Compact(space::ContinuousMemMapAllocSpace* target_space,
space::ContinuousMemMapAllocSpace* source_space) {
CHECK(kMovingCollector);
CHECK_NE(target_space, source_space) << "In-place compaction currently unsupported";
if (target_space != source_space) {
semi_space_collector_->SetFromSpace(source_space);
semi_space_collector_->SetToSpace(target_space);
semi_space_collector_->Run(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.";
}
gc_complete_lock_->AssertNotHeld(self);
if (!StartGC(self)) {
return collector::kGcTypeNone;
}
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;
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 (collector_type_ == kCollectorTypeSS) {
DCHECK(current_allocator_ == kAllocatorTypeBumpPointer ||
current_allocator_ == kAllocatorTypeTLAB);
gc_type = semi_space_collector_->GetGcType();
CHECK(temp_space_->IsEmpty());
semi_space_collector_->SetFromSpace(bump_pointer_space_);
semi_space_collector_->SetToSpace(temp_space_);
mprotect(temp_space_->Begin(), temp_space_->Capacity(), PROT_READ | PROT_WRITE);
collector = semi_space_collector_;
gc_type = collector::kGcTypeFull;
} else if (current_allocator_ == kAllocatorTypeRosAlloc ||
current_allocator_ == kAllocatorTypeDlMalloc) {
for (const auto& cur_collector : garbage_collectors_) {
if (cur_collector->IsConcurrent() == concurrent_gc_ &&
cur_collector->GetGcType() == gc_type) {
collector = cur_collector;
break;
}
}
} else {
LOG(FATAL) << "Invalid current allocator " << current_allocator_;
}
CHECK(collector != nullptr)
<< "Could not find garbage collector with concurrent=" << concurrent_gc_
<< " and type=" << gc_type;
ATRACE_BEGIN(StringPrintf("%s %s GC", PrettyCause(gc_cause), collector->GetName()).c_str());
collector->Run(clear_soft_references);
total_objects_freed_ever_ += collector->GetFreedObjects();
total_bytes_freed_ever_ += collector->GetFreedBytes();
// Enqueue cleared references.
Locks::mutator_lock_->AssertNotHeld(self);
EnqueueClearedReferences();
// Grow the heap so that we know when to perform the next GC.
GrowForUtilization(gc_type, collector->GetDurationNs());
if (CareAboutPauseTimes()) {
const size_t duration = collector->GetDurationNs();
std::vector<uint64_t> pauses = collector->GetPauseTimes();
// GC for alloc pauses the allocating thread, so consider it as a pause.
bool was_slow = duration > long_gc_log_threshold_ ||
(gc_cause == kGcCauseForAlloc && duration > long_pause_log_threshold_);
if (!was_slow) {
for (uint64_t pause : pauses) {
was_slow = was_slow || pause > long_pause_log_threshold_;
}
}
if (was_slow) {
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 < pauses.size(); ++i) {
pause_string << PrettyDuration((pauses[i] / 1000) * 1000)
<< ((i != pauses.size() - 1) ? ", " : "");
}
LOG(INFO) << gc_cause << " " << collector->GetName()
<< " GC freed " << collector->GetFreedObjects() << "("
<< PrettySize(collector->GetFreedBytes()) << ") AllocSpace objects, "
<< collector->GetFreedLargeObjects() << "("
<< PrettySize(collector->GetFreedLargeObjectBytes()) << ") LOS objects, "
<< percent_free << "% free, " << PrettySize(current_heap_size) << "/"
<< PrettySize(total_memory) << ", " << "paused " << pause_string.str()
<< " total " << PrettyDuration((duration / 1000) * 1000);
if (VLOG_IS_ON(heap)) {
LOG(INFO) << Dumpable<TimingLogger>(collector->GetTimings());
}
}
}
FinishGC(self, gc_type);
ATRACE_END();
// Inform DDMS that a GC completed.
Dbg::GcDidFinish();
return gc_type;
}
bool Heap::StartGC(Thread* self) {
MutexLock mu(self, *gc_complete_lock_);
// Ensure there is only one GC at a time.
WaitForGcToCompleteLocked(self);
// TODO: if another thread beat this one to do the GC, perhaps we should just return here?
// Not doing at the moment to ensure soft references are cleared.
// GC can be disabled if someone has a used GetPrimitiveArrayCritical.
if (gc_disable_count_ != 0) {
LOG(WARNING) << "Skipping GC due to disable count " << gc_disable_count_;
return false;
}
is_gc_running_ = true;
return true;
}
void Heap::FinishGC(Thread* self, collector::GcType gc_type) {
MutexLock mu(self, *gc_complete_lock_);
is_gc_running_ = false;
last_gc_type_ = gc_type;
// Wake anyone who may have been waiting for the GC to complete.
gc_complete_cond_->Broadcast(self);
}
static mirror::Object* RootMatchesObjectVisitor(mirror::Object* root, void* arg) {
mirror::Object* obj = reinterpret_cast<mirror::Object*>(arg);
if (root == obj) {
LOG(INFO) << "Object " << obj << " is a root";
}
return 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)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_)
: heap_(heap), failed_(false) {}
bool Failed() const {
return failed_;
}
// TODO: Fix lock analysis to not use NO_THREAD_SAFETY_ANALYSIS, requires support for smarter
// analysis on visitors.
void operator()(const mirror::Object* obj, const mirror::Object* ref,
const MemberOffset& offset, bool /* is_static */) const
NO_THREAD_SAFETY_ANALYSIS {
// Verify that the reference is live.
if (UNLIKELY(ref != NULL && !IsLive(ref))) {
accounting::CardTable* card_table = heap_->GetCardTable();
accounting::ObjectStack* alloc_stack = heap_->allocation_stack_.get();
accounting::ObjectStack* live_stack = heap_->live_stack_.get();
if (!failed_) {
// Print message on only on first failure to prevent spam.
LOG(ERROR) << "!!!!!!!!!!!!!!Heap corruption detected!!!!!!!!!!!!!!!!!!!";
failed_ = true;
}
if (obj != nullptr) {
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";
}
// Attmept 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::SpaceBitmap* bitmap = heap_->GetLiveBitmap()->GetContinuousSpaceBitmap(obj);
// Print out how the object is live.
if (bitmap != NULL && 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, false, false);
// 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, false, false);
} else {
LOG(ERROR) << "Root references dead object " << ref << "\nRef type " << PrettyTypeOf(ref);
}
}
}
bool IsLive(const mirror::Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
return heap_->IsLiveObjectLocked(obj, true, false, true);
}
static mirror::Object* VerifyRoots(mirror::Object* root, void* arg) {
VerifyReferenceVisitor* visitor = reinterpret_cast<VerifyReferenceVisitor*>(arg);
(*visitor)(nullptr, root, MemberOffset(0), true);
return root;
}
private:
Heap* const heap_;
mutable bool failed_;
};
// Verify all references within an object, for use with HeapBitmap::Visit.
class VerifyObjectVisitor {
public:
explicit VerifyObjectVisitor(Heap* heap) : heap_(heap), failed_(false) {}
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_);
// The class doesn't count as a reference but we should verify it anyways.
collector::MarkSweep::VisitObjectReferences(obj, visitor, true);
if (obj->GetClass()->IsReferenceClass()) {
visitor(obj, heap_->GetReferenceReferent(obj), MemberOffset(0), false);
}
failed_ = failed_ || visitor.Failed();
}
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);
}
bool Failed() const {
return failed_;
}
private:
Heap* const heap_;
mutable bool failed_;
};
// Must do this with mutators suspended since we are directly accessing the allocation stacks.
bool Heap::VerifyHeapReferences() {
Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
// Lets sort our allocation stacks so that we can efficiently binary search them.
allocation_stack_->Sort();
live_stack_->Sort();
VerifyObjectVisitor visitor(this);
// 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::VerifyRoots, &visitor, false, false);
if (visitor.Failed()) {
// 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() << ": ");
}
DumpSpaces();
return false;
}
return true;
}
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()(const mirror::Object* obj, const mirror::Object* ref, const MemberOffset& offset,
bool is_static) const NO_THREAD_SAFETY_ANALYSIS {
// 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 != NULL && !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)) {
// 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(const_cast<mirror::Object*>(ref))) {
if (live_stack->ContainsSorted(const_cast<mirror::Object*>(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()) {
const mirror::Class* klass = is_static ? obj->AsClass() : obj->GetClass();
CHECK(klass != NULL);
const mirror::ObjectArray<mirror::ArtField>* fields = is_static ? klass->GetSFields()
: klass->GetIFields();
CHECK(fields != NULL);
for (int32_t i = 0; i < fields->GetLength(); ++i) {
const 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 {
const 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_));
collector::MarkSweep::VisitObjectReferences(const_cast<mirror::Object*>(obj), visitor, true);
}
bool Failed() const {
return failed_;
}
private:
Heap* const heap_;
bool failed_;
};
bool Heap::VerifyMissingCardMarks() {
Locks::mutator_lock_->AssertExclusiveHeld(Thread::Current());
// We need to sort the live stack since we binary search it.
live_stack_->Sort();
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) {
visitor(*it);
}
if (visitor.Failed()) {
DumpSpaces();
return false;
}
return true;
}
void Heap::SwapStacks() {
allocation_stack_.swap(live_stack_);
}
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;
}
void Heap::ProcessCards(TimingLogger& 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);
if (table != nullptr) {
const char* name = space->IsZygoteSpace() ? "ZygoteModUnionClearCards" :
"ImageModUnionClearCards";
TimingLogger::ScopedSplit split(name, &timings);
table->ClearCards();
} else if (space->GetType() != space::kSpaceTypeBumpPointerSpace) {
TimingLogger::ScopedSplit split("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: Don't need to use atomic.
// 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 mirror::Object* IdentityCallback(mirror::Object* obj, void*) {
return obj;
}
void Heap::PreGcVerification(collector::GarbageCollector* gc) {
ThreadList* thread_list = Runtime::Current()->GetThreadList();
Thread* self = Thread::Current();
if (verify_pre_gc_heap_) {
thread_list->SuspendAll();
{
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
if (!VerifyHeapReferences()) {
LOG(FATAL) << "Pre " << gc->GetName() << " heap verification failed";
}
}
thread_list->ResumeAll();
}
// Check that all objects which reference things in the live stack are on dirty cards.
if (verify_missing_card_marks_) {
thread_list->SuspendAll();
{
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
SwapStacks();
// Sort the live stack so that we can quickly binary search it later.
if (!VerifyMissingCardMarks()) {
LOG(FATAL) << "Pre " << gc->GetName() << " missing card mark verification failed";
}
SwapStacks();
}
thread_list->ResumeAll();
}
if (verify_mod_union_table_) {
thread_list->SuspendAll();
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(IdentityCallback, nullptr);
mod_union_table->Verify();
}
thread_list->ResumeAll();
}
}
void Heap::PreSweepingGcVerification(collector::GarbageCollector* gc) {
// Called before sweeping occurs since we want to make sure we are not going so reclaim any
// reachable objects.
if (verify_post_gc_heap_) {
Thread* self = Thread::Current();
CHECK_NE(self->GetState(), kRunnable);
{
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
// Swapping bound bitmaps does nothing.
gc->SwapBitmaps();
if (!VerifyHeapReferences()) {
LOG(FATAL) << "Pre sweeping " << gc->GetName() << " GC verification failed";
}
gc->SwapBitmaps();
}
}
}
void Heap::PostGcVerification(collector::GarbageCollector* gc) {
if (verify_system_weaks_) {
Thread* self = Thread::Current();
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
collector::MarkSweep* mark_sweep = down_cast<collector::MarkSweep*>(gc);
mark_sweep->VerifySystemWeaks();
}
}
collector::GcType Heap::WaitForGcToComplete(Thread* self) {
ScopedThreadStateChange tsc(self, kWaitingForGcToComplete);
MutexLock mu(self, *gc_complete_lock_);
return WaitForGcToCompleteLocked(self);
}
collector::GcType Heap::WaitForGcToCompleteLocked(Thread* self) {
collector::GcType last_gc_type = collector::kGcTypeNone;
uint64_t wait_start = NanoTime();
while (is_gc_running_) {
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);
}
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()) / GetTotalMemory());
}
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) {
DCHECK(!IsInTempSpace(obj));
if (bump_pointer_space_->HasAddress(obj)) {
return true;
}
}
return false;
}
bool Heap::IsInTempSpace(const mirror::Object* obj) const {
if (temp_space_->HasAddress(obj) && !temp_space_->Contains(obj)) {
return true;
}
return false;
}
void Heap::UpdateMaxNativeFootprint() {
size_t native_size = native_bytes_allocated_;
// 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_ = target_size;
native_footprint_limit_ = 2 * target_size - native_size;
}
void Heap::GrowForUtilization(collector::GcType gc_type, uint64_t gc_duration) {
// 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 size_t bytes_allocated = GetBytesAllocated();
last_gc_size_ = bytes_allocated;
last_gc_time_ns_ = NanoTime();
size_t target_size;
if (gc_type != collector::kGcTypeSticky) {
// Grow the heap for non sticky GC.
target_size = bytes_allocated / GetTargetHeapUtilization();
if (target_size > bytes_allocated + max_free_) {
target_size = bytes_allocated + max_free_;
} else if (target_size < bytes_allocated + min_free_) {
target_size = bytes_allocated + min_free_;
}
native_need_to_run_finalization_ = true;
next_gc_type_ = collector::kGcTypeSticky;
} else {
// Based on how close the current heap size is to the target size, decide
// whether or not to do a partial or sticky GC next.
if (bytes_allocated + min_free_ <= max_allowed_footprint_) {
next_gc_type_ = collector::kGcTypeSticky;
} else {
next_gc_type_ = collector::kGcTypePartial;
}
// 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, max_allowed_footprint_);
}
}
if (!ignore_max_footprint_) {
SetIdealFootprint(target_size);
if (concurrent_gc_) {
// Calculate when to perform the next ConcurrentGC.
// Calculate the estimated GC duration.
double gc_duration_seconds = NsToMs(gc_duration) / 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::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 straight away.
concurrent_start_bytes_ = bytes_allocated;
} else {
// 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,
bytes_allocated);
}
DCHECK_LE(concurrent_start_bytes_, max_allowed_footprint_);
DCHECK_LE(max_allowed_footprint_, growth_limit_);
}
}
}
void Heap::ClearGrowthLimit() {
growth_limit_ = capacity_;
non_moving_space_->ClearGrowthLimit();
}
void Heap::SetReferenceOffsets(MemberOffset reference_referent_offset,
MemberOffset reference_queue_offset,
MemberOffset reference_queueNext_offset,
MemberOffset reference_pendingNext_offset,
MemberOffset finalizer_reference_zombie_offset) {
reference_referent_offset_ = reference_referent_offset;
reference_queue_offset_ = reference_queue_offset;
reference_queueNext_offset_ = reference_queueNext_offset;
reference_pendingNext_offset_ = reference_pendingNext_offset;
finalizer_reference_zombie_offset_ = finalizer_reference_zombie_offset;
CHECK_NE(reference_referent_offset_.Uint32Value(), 0U);
CHECK_NE(reference_queue_offset_.Uint32Value(), 0U);
CHECK_NE(reference_queueNext_offset_.Uint32Value(), 0U);
CHECK_NE(reference_pendingNext_offset_.Uint32Value(), 0U);
CHECK_NE(finalizer_reference_zombie_offset_.Uint32Value(), 0U);
}
void Heap::SetReferenceReferent(mirror::Object* reference, mirror::Object* referent) {
DCHECK(reference != NULL);
DCHECK_NE(reference_referent_offset_.Uint32Value(), 0U);
reference->SetFieldObject(reference_referent_offset_, referent, true);
}
mirror::Object* Heap::GetReferenceReferent(mirror::Object* reference) {
DCHECK(reference != NULL);
DCHECK_NE(reference_referent_offset_.Uint32Value(), 0U);
return reference->GetFieldObject<mirror::Object*>(reference_referent_offset_, true);
}
void Heap::AddFinalizerReference(Thread* self, mirror::Object* object) {
ScopedObjectAccess soa(self);
JValue result;
ArgArray arg_array(NULL, 0);
arg_array.Append(reinterpret_cast<uint32_t>(object));
soa.DecodeMethod(WellKnownClasses::java_lang_ref_FinalizerReference_add)->Invoke(self,
arg_array.GetArray(), arg_array.GetNumBytes(), &result, 'V');
}
void Heap::EnqueueClearedReferences() {
if (!cleared_references_.IsEmpty()) {
// When a runtime isn't started there are no reference queues to care about so ignore.
if (LIKELY(Runtime::Current()->IsStarted())) {
ScopedObjectAccess soa(Thread::Current());
JValue result;
ArgArray arg_array(NULL, 0);
arg_array.Append(reinterpret_cast<uint32_t>(cleared_references_.GetList()));
soa.DecodeMethod(WellKnownClasses::java_lang_ref_ReferenceQueue_add)->Invoke(soa.Self(),
arg_array.GetArray(), arg_array.GetNumBytes(), &result, 'V');
}
cleared_references_.Clear();
}
}
void Heap::RequestConcurrentGC(Thread* self) {
// Make sure that we can do a concurrent GC.
Runtime* runtime = Runtime::Current();
if (runtime == NULL || !runtime->IsFinishedStarting() || runtime->IsShuttingDown(self) ||
self->IsHandlingStackOverflow()) {
return;
}
// We already have a request pending, no reason to start more until we update
// concurrent_start_bytes_.
concurrent_start_bytes_ = std::numeric_limits<size_t>::max();
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(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::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.
uint64_t ms_time = MilliTime();
// Don't bother trimming the alloc space if a heap trim occurred in the last two seconds.
if (ms_time - last_trim_time_ms_ < 2 * 1000) {
return;
}
Thread* self = Thread::Current();
Runtime* runtime = Runtime::Current();
if (runtime == nullptr || !runtime->IsFinishedStarting() || runtime->IsShuttingDown(self)) {
// 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;
}
last_trim_time_ms_ = ms_time;
// Trim only if we do not currently care about pause times.
if (!CareAboutPauseTimes()) {
JNIEnv* env = self->GetJniEnv();
DCHECK(WellKnownClasses::java_lang_Daemons != NULL);
DCHECK(WellKnownClasses::java_lang_Daemons_requestHeapTrim != NULL);
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::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);
}
void Heap::RegisterNativeAllocation(JNIEnv* env, int 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.
native_bytes_allocated_.FetchAndAdd(bytes);
if (static_cast<size_t>(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 (static_cast<size_t>(native_bytes_allocated_) > native_footprint_limit_) {
if (WaitForGcToComplete(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 (static_cast<size_t>(native_bytes_allocated_) > native_footprint_limit_) {
CollectGarbageInternal(gc_type, kGcCauseForAlloc, 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 (concurrent_gc_) {
RequestConcurrentGC(self);
} else {
CollectGarbageInternal(gc_type, kGcCauseForAlloc, false);
}
}
}
}
void Heap::RegisterNativeFree(JNIEnv* env, int bytes) {
int expected_size, new_size;
do {
expected_size = native_bytes_allocated_.Load();
new_size = expected_size - bytes;
if (UNLIKELY(new_size < 0)) {
ScopedObjectAccess soa(env);
env->ThrowNew(WellKnownClasses::java_lang_RuntimeException,
StringPrintf("Attempted to free %d native bytes with only %d native bytes "
"registered as allocated", bytes, expected_size).c_str());
break;
}
} while (!native_bytes_allocated_.CompareAndSwap(expected_size, new_size));
}
int64_t Heap::GetTotalMemory() const {
int64_t ret = 0;
for (const auto& space : continuous_spaces_) {
// Currently don't include the image space.
if (!space->IsImageSpace()) {
ret += space->Size();
}
}
for (const auto& space : discontinuous_spaces_) {
if (space->IsLargeObjectSpace()) {
ret += space->AsLargeObjectSpace()->GetBytesAllocated();
}
}
return ret;
}
void Heap::AddModUnionTable(accounting::ModUnionTable* mod_union_table) {
DCHECK(mod_union_table != nullptr);
mod_union_tables_.Put(mod_union_table->GetSpace(), mod_union_table);
}
} // namespace gc
} // namespace art