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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 "base/stl_util.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-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/sticky_mark_sweep.h"
#include "gc/space/image_space.h"
#include "gc/space/large_object_space.h"
#include "gc/space/space-inl.h"
#include "image.h"
#include "invoke_arg_array_builder.h"
#include "mirror/class-inl.h"
#include "mirror/field-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 "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 {
namespace gc {
// When to create a log message about a slow GC, 100ms.
static const uint64_t kSlowGcThreshold = MsToNs(100);
// When to create a log message about a long pause, 5ms.
static const uint64_t kLongGcPauseThreshold = MsToNs(5);
static const bool kDumpGcPerformanceOnShutdown = false;
// Minimum amount of remaining bytes before a concurrent GC is triggered.
static const size_t kMinConcurrentRemainingBytes = 128 * KB;
const double Heap::kDefaultTargetUtilization = 0.5;
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& original_image_file_name, bool concurrent_gc)
: alloc_space_(NULL),
card_table_(NULL),
concurrent_gc_(concurrent_gc),
have_zygote_space_(false),
reference_queue_lock_(NULL),
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),
concurrent_start_bytes_(concurrent_gc ? initial_size - (kMinConcurrentRemainingBytes)
: std::numeric_limits<size_t>::max()),
total_bytes_freed_ever_(0),
total_objects_freed_ever_(0),
large_object_threshold_(3 * kPageSize),
num_bytes_allocated_(0),
process_state_(PROCESS_STATE_TOP),
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_(2 * MB),
min_remaining_space_for_sticky_gc_(1 * MB),
last_trim_time_ms_(0),
allocation_rate_(0),
max_allocation_stack_size_(kDesiredHeapVerification > kNoHeapVerification? KB : MB),
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),
measure_allocation_time_(false),
total_allocation_time_(0),
verify_object_mode_(kHeapVerificationNotPermitted) {
if (VLOG_IS_ON(heap) || VLOG_IS_ON(startup)) {
LOG(INFO) << "Heap() entering";
}
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 = NULL;
std::string image_file_name(original_image_file_name);
if (!image_file_name.empty()) {
space::ImageSpace* image_space = space::ImageSpace::Create(image_file_name);
CHECK(image_space != NULL) << "Failed to create space for " << image_file_name;
AddContinuousSpace(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 =
reinterpret_cast<byte*>(RoundUp(reinterpret_cast<uintptr_t>(oat_file_end_addr),
kPageSize));
}
}
// Allocate the large object space.
const bool kUseFreeListSpaceForLOS = false;
if (kUseFreeListSpaceForLOS) {
large_object_space_ = space::FreeListSpace::Create("large object space", NULL, capacity);
} else {
large_object_space_ = space::LargeObjectMapSpace::Create("large object space");
}
CHECK(large_object_space_ != NULL) << "Failed to create large object space";
AddDiscontinuousSpace(large_object_space_);
alloc_space_ = space::DlMallocSpace::Create("alloc space",
initial_size,
growth_limit, capacity,
requested_alloc_space_begin);
CHECK(alloc_space_ != NULL) << "Failed to create alloc space";
alloc_space_->SetFootprintLimit(alloc_space_->Capacity());
AddContinuousSpace(alloc_space_);
// Compute heap capacity. Continuous spaces are sorted in order of Begin().
byte* heap_begin = continuous_spaces_.front()->Begin();
size_t heap_capacity = continuous_spaces_.back()->End() - continuous_spaces_.front()->Begin();
if (continuous_spaces_.back()->IsDlMallocSpace()) {
heap_capacity += continuous_spaces_.back()->AsDlMallocSpace()->NonGrowthLimitCapacity();
}
// Mark image objects in the live bitmap
// TODO: C++0x
typedef std::vector<space::ContinuousSpace*>::iterator It;
for (It it = continuous_spaces_.begin(); it != continuous_spaces_.end(); ++it) {
space::ContinuousSpace* space = *it;
if (space->IsImageSpace()) {
space::ImageSpace* image_space = space->AsImageSpace();
image_space->RecordImageAllocations(image_space->GetLiveBitmap());
}
}
// Allocate the card table.
card_table_.reset(accounting::CardTable::Create(heap_begin, heap_capacity));
CHECK(card_table_.get() != NULL) << "Failed to create card table";
image_mod_union_table_.reset(new accounting::ModUnionTableToZygoteAllocspace(this));
CHECK(image_mod_union_table_.get() != NULL) << "Failed to create image mod-union table";
zygote_mod_union_table_.reset(new accounting::ModUnionTableCardCache(this));
CHECK(zygote_mod_union_table_.get() != NULL) << "Failed to create Zygote 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_));
// Create the reference queue lock, this is required so for parrallel object scanning in the GC.
reference_queue_lock_ = new Mutex("reference queue lock");
last_gc_time_ns_ = NanoTime();
last_gc_size_ = GetBytesAllocated();
// Create our garbage collectors.
for (size_t i = 0; i < 2; ++i) {
const bool concurrent = i != 0;
mark_sweep_collectors_.push_back(new collector::MarkSweep(this, concurrent));
mark_sweep_collectors_.push_back(new collector::PartialMarkSweep(this, concurrent));
mark_sweep_collectors_.push_back(new collector::StickyMarkSweep(this, concurrent));
}
CHECK(max_allowed_footprint_ != 0);
if (VLOG_IS_ON(heap) || VLOG_IS_ON(startup)) {
LOG(INFO) << "Heap() exiting";
}
}
void Heap::CreateThreadPool() {
// TODO: Make sysconf(_SC_NPROCESSORS_CONF) be a helper function?
// Use the number of processors - 1 since the thread doing the GC does work while its waiting for
// workers to complete.
thread_pool_.reset(new ThreadPool(1)); // new ThreadPool(sysconf(_SC_NPROCESSORS_CONF) - 1));
}
void Heap::DeleteThreadPool() {
thread_pool_.reset(NULL);
}
// Sort spaces based on begin address
struct ContinuousSpaceSorter {
bool operator()(const space::ContinuousSpace* a, const space::ContinuousSpace* b) const {
return a->Begin() < b->Begin();
}
};
void Heap::UpdateProcessState(ProcessState process_state) {
process_state_ = process_state;
}
void Heap::AddContinuousSpace(space::ContinuousSpace* space) {
WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
DCHECK(space != NULL);
DCHECK(space->GetLiveBitmap() != NULL);
live_bitmap_->AddContinuousSpaceBitmap(space->GetLiveBitmap());
DCHECK(space->GetMarkBitmap() != NULL);
mark_bitmap_->AddContinuousSpaceBitmap(space->GetMarkBitmap());
continuous_spaces_.push_back(space);
if (space->IsDlMallocSpace() && !space->IsLargeObjectSpace()) {
alloc_space_ = space->AsDlMallocSpace();
}
// Ensure that spaces remain sorted in increasing order of start address (required for CMS finger)
std::sort(continuous_spaces_.begin(), continuous_spaces_.end(), ContinuousSpaceSorter());
// Ensure that ImageSpaces < ZygoteSpaces < AllocSpaces so that we can do address based checks to
// avoid redundant marking.
bool seen_zygote = false, seen_alloc = false;
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(); it != continuous_spaces_.end(); ++it) {
space::ContinuousSpace* space = *it;
if (space->IsImageSpace()) {
DCHECK(!seen_zygote);
DCHECK(!seen_alloc);
} else if (space->IsZygoteSpace()) {
DCHECK(!seen_alloc);
seen_zygote = true;
} else if (space->IsDlMallocSpace()) {
seen_alloc = true;
}
}
}
void Heap::AddDiscontinuousSpace(space::DiscontinuousSpace* space) {
WriterMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
DCHECK(space != NULL);
DCHECK(space->GetLiveObjects() != NULL);
live_bitmap_->AddDiscontinuousObjectSet(space->GetLiveObjects());
DCHECK(space->GetMarkObjects() != NULL);
mark_bitmap_->AddDiscontinuousObjectSet(space->GetMarkObjects());
discontinuous_spaces_.push_back(space);
}
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.
// TODO: C++0x
uint64_t total_paused_time = 0;
typedef std::vector<collector::MarkSweep*>::const_iterator It;
for (It it = mark_sweep_collectors_.begin();
it != mark_sweep_collectors_.end(); ++it) {
collector::MarkSweep* collector = *it;
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 = (*it)->GetTotalPausedTimeNs();
double seconds = NsToMs(logger.GetTotalNs()) / 1000.0;
const uint64_t freed_bytes = collector->GetTotalFreedBytes();
const uint64_t freed_objects = collector->GetTotalFreedObjects();
os << collector->GetName() << " total time: " << PrettyDuration(total_ns) << "\n"
<< collector->GetName() << " paused time: " << PrettyDuration(total_pause_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;
size_t total_objects_allocated = GetObjectsAllocatedEver();
size_t total_bytes_allocated = GetBytesAllocatedEver();
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";
}
os << "Total number of allocations: " << total_objects_allocated << "\n";
os << "Total bytes allocated " << PrettySize(total_bytes_allocated) << "\n";
if (measure_allocation_time_) {
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";
}
Heap::~Heap() {
if (kDumpGcPerformanceOnShutdown) {
DumpGcPerformanceInfo(LOG(INFO));
}
STLDeleteElements(&mark_sweep_collectors_);
// If we don't reset then the mark stack complains in it's destructor.
allocation_stack_->Reset();
live_stack_->Reset();
VLOG(heap) << "~Heap()";
// We can't take the heap lock here because there might be a daemon thread suspended with the
// heap lock held. We know though that no non-daemon threads are executing, and we know that
// all daemon threads are suspended, and we also know that the threads list have been deleted, so
// those threads can't resume. We're the only running thread, and we can do whatever we like...
STLDeleteElements(&continuous_spaces_);
STLDeleteElements(&discontinuous_spaces_);
delete gc_complete_lock_;
delete reference_queue_lock_;
}
space::ContinuousSpace* Heap::FindContinuousSpaceFromObject(const mirror::Object* obj,
bool fail_ok) const {
// TODO: C++0x auto
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
if ((*it)->Contains(obj)) {
return *it;
}
}
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 {
// TODO: C++0x auto
typedef std::vector<space::DiscontinuousSpace*>::const_iterator It;
for (It it = discontinuous_spaces_.begin(), end = discontinuous_spaces_.end(); it != end; ++it) {
if ((*it)->Contains(obj)) {
return *it;
}
}
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 {
// TODO: C++0x auto
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
if ((*it)->IsImageSpace()) {
return (*it)->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);
}
}
mirror::Object* Heap::AllocObject(Thread* self, mirror::Class* c, size_t byte_count) {
DCHECK(c == NULL || (c->IsClassClass() && byte_count >= sizeof(mirror::Class)) ||
(c->IsVariableSize() || c->GetObjectSize() == byte_count) ||
strlen(ClassHelper(c).GetDescriptor()) == 0);
DCHECK_GE(byte_count, sizeof(mirror::Object));
mirror::Object* obj = NULL;
size_t size = 0;
uint64_t allocation_start = 0;
if (measure_allocation_time_) {
allocation_start = NanoTime() / kTimeAdjust;
}
// We need to have a zygote space or else our newly allocated large object can end up in the
// Zygote resulting in it being prematurely freed.
// We can only do this for primive objects since large objects will not be within the card table
// range. This also means that we rely on SetClass not dirtying the object's card.
if (byte_count >= large_object_threshold_ && have_zygote_space_ && c->IsPrimitiveArray()) {
size = RoundUp(byte_count, kPageSize);
obj = Allocate(self, large_object_space_, size);
// Make sure that our large object didn't get placed anywhere within the space interval or else
// it breaks the immune range.
DCHECK(obj == NULL ||
reinterpret_cast<byte*>(obj) < continuous_spaces_.front()->Begin() ||
reinterpret_cast<byte*>(obj) >= continuous_spaces_.back()->End());
} else {
obj = Allocate(self, alloc_space_, byte_count);
// Ensure that we did not allocate into a zygote space.
DCHECK(obj == NULL || !have_zygote_space_ || !FindSpaceFromObject(obj, false)->IsZygoteSpace());
size = alloc_space_->AllocationSize(obj);
}
if (LIKELY(obj != NULL)) {
obj->SetClass(c);
// Record allocation after since we want to use the atomic add for the atomic fence to guard
// the SetClass since we do not want the class to appear NULL in another thread.
RecordAllocation(size, obj);
if (Dbg::IsAllocTrackingEnabled()) {
Dbg::RecordAllocation(c, byte_count);
}
if (static_cast<size_t>(num_bytes_allocated_) >= concurrent_start_bytes_) {
// 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();
// The SirtRef is necessary since the calls in RequestConcurrentGC are a safepoint.
SirtRef<mirror::Object> ref(self, obj);
RequestConcurrentGC(self);
}
VerifyObject(obj);
if (measure_allocation_time_) {
total_allocation_time_ += NanoTime() / kTimeAdjust - allocation_start;
}
return obj;
}
std::ostringstream oss;
int64_t total_bytes_free = GetFreeMemory();
uint64_t alloc_space_size = alloc_space_->GetBytesAllocated();
uint64_t large_object_size = large_object_space_->GetObjectsAllocated();
oss << "Failed to allocate a " << byte_count << " byte allocation with " << total_bytes_free
<< " free bytes; allocation space size " << alloc_space_size
<< "; large object space size " << large_object_size;
// If the allocation failed due to fragmentation, print out the largest continuous allocation.
if (total_bytes_free >= byte_count) {
size_t max_contiguous_allocation = 0;
// TODO: C++0x auto
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
space::ContinuousSpace* space = *it;
if (space->IsDlMallocSpace()) {
space->AsDlMallocSpace()->Walk(MSpaceChunkCallback, &max_contiguous_allocation);
}
}
oss << "; failed due to fragmentation (largest possible contiguous allocation "
<< max_contiguous_allocation << " bytes)";
}
self->ThrowOutOfMemoryError(oss.str().c_str());
return NULL;
}
bool Heap::IsHeapAddress(const mirror::Object* obj) {
// Note: we deliberately don't take the lock here, and mustn't test anything that would
// require taking the lock.
if (obj == NULL) {
return true;
}
if (UNLIKELY(!IsAligned<kObjectAlignment>(obj))) {
return false;
}
return FindSpaceFromObject(obj, true) != NULL;
}
bool Heap::IsLiveObjectLocked(const mirror::Object* obj) {
//Locks::heap_bitmap_lock_->AssertReaderHeld(Thread::Current());
if (obj == NULL) {
return false;
}
if (UNLIKELY(!IsAligned<kObjectAlignment>(obj))) {
return false;
}
space::ContinuousSpace* cont_space = FindContinuousSpaceFromObject(obj, true);
if (cont_space != NULL) {
if (cont_space->GetLiveBitmap()->Test(obj)) {
return true;
}
} else {
space::DiscontinuousSpace* disc_space = FindDiscontinuousSpaceFromObject(obj, true);
if (disc_space != NULL) {
if (disc_space->GetLiveObjects()->Test(obj)) {
return true;
}
}
}
for (size_t i = 0; i < 5; ++i) {
if (allocation_stack_->Contains(const_cast<mirror::Object*>(obj)) ||
live_stack_->Contains(const_cast<mirror::Object*>(obj))) {
return true;
}
NanoSleep(MsToNs(10));
}
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() {
// TODO: C++0x auto
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
space::ContinuousSpace* space = *it;
accounting::SpaceBitmap* live_bitmap = space->GetLiveBitmap();
accounting::SpaceBitmap* mark_bitmap = space->GetMarkBitmap();
LOG(INFO) << space << " " << *space << "\n"
<< live_bitmap << " " << *live_bitmap << "\n"
<< mark_bitmap << " " << *mark_bitmap;
}
typedef std::vector<space::DiscontinuousSpace*>::const_iterator It2;
for (It2 it = discontinuous_spaces_.begin(), end = discontinuous_spaces_.end(); it != end; ++it) {
space::DiscontinuousSpace* space = *it;
LOG(INFO) << space << " " << *space << "\n";
}
}
void Heap::VerifyObjectBody(const mirror::Object* obj) {
if (UNLIKELY(!IsAligned<kObjectAlignment>(obj))) {
LOG(FATAL) << "Object isn't aligned: " << obj;
}
if (UNLIKELY(GetObjectsAllocated() <= 10)) { // Ignore early dawn of the universe verifications.
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::RecordAllocation(size_t size, mirror::Object* obj) {
DCHECK(obj != NULL);
DCHECK_GT(size, 0u);
num_bytes_allocated_ += size;
if (Runtime::Current()->HasStatsEnabled()) {
RuntimeStats* thread_stats = Thread::Current()->GetStats();
++thread_stats->allocated_objects;
thread_stats->allocated_bytes += size;
// TODO: Update these atomically.
RuntimeStats* global_stats = Runtime::Current()->GetStats();
++global_stats->allocated_objects;
global_stats->allocated_bytes += size;
}
// This is safe to do since the GC will never free objects which are neither in the allocation
// stack or the live bitmap.
while (!allocation_stack_->AtomicPushBack(obj)) {
CollectGarbageInternal(collector::kGcTypeSticky, kGcCauseForAlloc, false);
}
}
void Heap::RecordFree(size_t freed_objects, size_t freed_bytes) {
DCHECK_LE(freed_bytes, static_cast<size_t>(num_bytes_allocated_));
num_bytes_allocated_ -= 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::TryToAllocate(Thread* self, space::AllocSpace* space, size_t alloc_size,
bool grow) {
// Should we try to use a CAS here and fix up num_bytes_allocated_ later with AllocationSize?
if (num_bytes_allocated_ + alloc_size > max_allowed_footprint_) {
// max_allowed_footprint_ <= growth_limit_ so it is safe to check in here.
if (num_bytes_allocated_ + alloc_size > growth_limit_) {
// Completely out of memory.
return NULL;
}
}
return space->Alloc(self, alloc_size);
}
mirror::Object* Heap::Allocate(Thread* self, space::AllocSpace* space, size_t alloc_size) {
// Since allocation can cause a GC which will need to SuspendAll, make sure all allocations are
// done in the runnable state where suspension is expected.
DCHECK_EQ(self->GetState(), kRunnable);
self->AssertThreadSuspensionIsAllowable();
mirror::Object* ptr = TryToAllocate(self, space, alloc_size, false);
if (ptr != NULL) {
return ptr;
}
// The allocation failed. If the GC is running, block until it completes, and then retry the
// allocation.
collector::GcType last_gc = WaitForConcurrentGcToComplete(self);
if (last_gc != collector::kGcTypeNone) {
// A GC was in progress and we blocked, retry allocation now that memory has been freed.
ptr = TryToAllocate(self, space, alloc_size, false);
if (ptr != NULL) {
return ptr;
}
}
// Loop through our different Gc types and try to Gc until we get enough free memory.
for (size_t i = static_cast<size_t>(last_gc) + 1;
i < static_cast<size_t>(collector::kGcTypeMax); ++i) {
bool run_gc = false;
collector::GcType gc_type = static_cast<collector::GcType>(i);
switch (gc_type) {
case collector::kGcTypeSticky: {
const size_t alloc_space_size = alloc_space_->Size();
run_gc = alloc_space_size > min_alloc_space_size_for_sticky_gc_ &&
alloc_space_->Capacity() - alloc_space_size >= min_remaining_space_for_sticky_gc_;
break;
}
case collector::kGcTypePartial:
run_gc = have_zygote_space_;
break;
case collector::kGcTypeFull:
run_gc = true;
break;
default:
break;
}
if (run_gc) {
// If we actually ran a different type of Gc than requested, we can skip the index forwards.
collector::GcType gc_type_ran = CollectGarbageInternal(gc_type, kGcCauseForAlloc, false);
DCHECK_GE(static_cast<size_t>(gc_type_ran), i);
i = static_cast<size_t>(gc_type_ran);
// Did we free sufficient memory for the allocation to succeed?
ptr = TryToAllocate(self, space, alloc_size, false);
if (ptr != NULL) {
return ptr;
}
}
}
// Allocations have failed after GCs; this is an exceptional state.
// Try harder, growing the heap if necessary.
ptr = TryToAllocate(self, space, alloc_size, true);
if (ptr != NULL) {
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.
// OLD-TODO: wait for the finalizers from the previous GC to finish
VLOG(gc) << "Forcing collection of SoftReferences for " << PrettySize(alloc_size)
<< " allocation";
// We don't need a WaitForConcurrentGcToComplete here either.
CollectGarbageInternal(collector::kGcTypeFull, kGcCauseForAlloc, true);
return TryToAllocate(self, space, alloc_size, true);
}
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;
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
space::ContinuousSpace* space = *it;
if (space->IsDlMallocSpace()) {
total += space->AsDlMallocSpace()->GetObjectsAllocated();
}
}
typedef std::vector<space::DiscontinuousSpace*>::const_iterator It2;
for (It2 it = discontinuous_spaces_.begin(), end = discontinuous_spaces_.end(); it != end; ++it) {
space::DiscontinuousSpace* space = *it;
total += space->AsLargeObjectSpace()->GetObjectsAllocated();
}
return total;
}
size_t Heap::GetObjectsAllocatedEver() const {
size_t total = 0;
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
space::ContinuousSpace* space = *it;
if (space->IsDlMallocSpace()) {
total += space->AsDlMallocSpace()->GetTotalObjectsAllocated();
}
}
typedef std::vector<space::DiscontinuousSpace*>::const_iterator It2;
for (It2 it = discontinuous_spaces_.begin(), end = discontinuous_spaces_.end(); it != end; ++it) {
space::DiscontinuousSpace* space = *it;
total += space->AsLargeObjectSpace()->GetTotalObjectsAllocated();
}
return total;
}
size_t Heap::GetBytesAllocatedEver() const {
size_t total = 0;
typedef std::vector<space::ContinuousSpace*>::const_iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
space::ContinuousSpace* space = *it;
if (space->IsDlMallocSpace()) {
total += space->AsDlMallocSpace()->GetTotalBytesAllocated();
}
}
typedef std::vector<space::DiscontinuousSpace*>::const_iterator It2;
for (It2 it = discontinuous_spaces_.begin(), end = discontinuous_spaces_.end(); it != end; ++it) {
space::DiscontinuousSpace* space = *it;
total += space->AsLargeObjectSpace()->GetTotalBytesAllocated();
}
return total;
}
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(o, *this);
}
// For MarkSweep::VisitObjectReferences.
void operator()(const mirror::Object* referrer, const mirror::Object* object,
const MemberOffset&, bool) const {
if (object == object_ && (max_count_ == 0 || referring_objects_.size() < max_count_)) {
referring_objects_.push_back(const_cast<mirror::Object*>(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.
Thread* self = Thread::Current();
WaitForConcurrentGcToComplete(self);
CollectGarbageInternal(collector::kGcTypeFull, kGcCauseExplicit, clear_soft_references);
}
void Heap::PreZygoteFork() {
static Mutex zygote_creation_lock_("zygote creation lock", kZygoteCreationLock);
// Do this before acquiring the zygote creation lock so that we don't get lock order violations.
CollectGarbage(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;
}
VLOG(heap) << "Starting PreZygoteFork with alloc space size " << PrettySize(alloc_space_->Size());
{
// Flush the alloc stack.
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
FlushAllocStack();
}
// Turns the current alloc space into a Zygote space and obtain the new alloc space composed
// of the remaining available heap memory.
space::DlMallocSpace* zygote_space = alloc_space_;
alloc_space_ = zygote_space->CreateZygoteSpace();
alloc_space_->SetFootprintLimit(alloc_space_->Capacity());
// Change the GC retention policy of the zygote space to only collect when full.
zygote_space->SetGcRetentionPolicy(space::kGcRetentionPolicyFullCollect);
AddContinuousSpace(alloc_space_);
have_zygote_space_ = true;
// Reset the cumulative loggers since we now have a few additional timing phases.
// TODO: C++0x
typedef std::vector<collector::MarkSweep*>::const_iterator It;
for (It it = mark_sweep_collectors_.begin(), end = mark_sweep_collectors_.end();
it != end; ++it) {
(*it)->ResetCumulativeStatistics();
}
}
void Heap::FlushAllocStack() {
MarkAllocStack(alloc_space_->GetLiveBitmap(), large_object_space_->GetLiveObjects(),
allocation_stack_.get());
allocation_stack_->Reset();
}
void Heap::MarkAllocStack(accounting::SpaceBitmap* bitmap, accounting::SpaceSetMap* large_objects,
accounting::ObjectStack* stack) {
mirror::Object** limit = stack->End();
for (mirror::Object** it = stack->Begin(); it != limit; ++it) {
const mirror::Object* obj = *it;
DCHECK(obj != NULL);
if (LIKELY(bitmap->HasAddress(obj))) {
bitmap->Set(obj);
} else {
large_objects->Set(obj);
}
}
}
void Heap::UnMarkAllocStack(accounting::SpaceBitmap* bitmap, accounting::SpaceSetMap* large_objects,
accounting::ObjectStack* stack) {
mirror::Object** limit = stack->End();
for (mirror::Object** it = stack->Begin(); it != limit; ++it) {
const mirror::Object* obj = *it;
DCHECK(obj != NULL);
if (LIKELY(bitmap->HasAddress(obj))) {
bitmap->Clear(obj);
} else {
large_objects->Clear(obj);
}
}
}
collector::GcType Heap::CollectGarbageInternal(collector::GcType gc_type, GcCause gc_cause,
bool clear_soft_references) {
Thread* self = Thread::Current();
switch (gc_cause) {
case kGcCauseForAlloc:
ATRACE_BEGIN("GC (alloc)");
break;
case kGcCauseBackground:
ATRACE_BEGIN("GC (background)");
break;
case kGcCauseExplicit:
ATRACE_BEGIN("GC (explicit)");
break;
}
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.";
}
// Ensure there is only one GC at a time.
bool start_collect = false;
while (!start_collect) {
{
MutexLock mu(self, *gc_complete_lock_);
if (!is_gc_running_) {
is_gc_running_ = true;
start_collect = true;
}
}
if (!start_collect) {
WaitForConcurrentGcToComplete(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_complete_lock_->AssertNotHeld(self);
if (gc_cause == kGcCauseForAlloc && Runtime::Current()->HasStatsEnabled()) {
++Runtime::Current()->GetStats()->gc_for_alloc_count;
++Thread::Current()->GetStats()->gc_for_alloc_count;
}
uint64_t gc_start_time_ns = NanoTime();
uint64_t gc_start_size = GetBytesAllocated();
// Approximate allocation rate in bytes / second.
if (UNLIKELY(gc_start_time_ns == last_gc_time_ns_)) {
LOG(WARNING) << "Timers are broken (gc_start_time == last_gc_time_).";
}
uint64_t ms_delta = NsToMs(gc_start_time_ns - last_gc_time_ns_);
if (ms_delta != 0) {
allocation_rate_ = ((gc_start_size - last_gc_size_) * 1000) / ms_delta;
VLOG(heap) << "Allocation rate: " << PrettySize(allocation_rate_) << "/s";
}
if (gc_type == collector::kGcTypeSticky &&
alloc_space_->Size() < min_alloc_space_size_for_sticky_gc_) {
gc_type = collector::kGcTypePartial;
}
DCHECK_LT(gc_type, collector::kGcTypeMax);
DCHECK_NE(gc_type, collector::kGcTypeNone);
collector::MarkSweep* collector = NULL;
typedef std::vector<collector::MarkSweep*>::iterator It;
for (It it = mark_sweep_collectors_.begin(), end = mark_sweep_collectors_.end();
it != end; ++it) {
collector::MarkSweep* cur_collector = *it;
if (cur_collector->IsConcurrent() == concurrent_gc_ && cur_collector->GetGcType() == gc_type) {
collector = cur_collector;
break;
}
}
CHECK(collector != NULL)
<< "Could not find garbage collector with concurrent=" << concurrent_gc_
<< " and type=" << gc_type;
collector->clear_soft_references_ = clear_soft_references;
collector->Run();
total_objects_freed_ever_ += collector->GetFreedObjects();
total_bytes_freed_ever_ += collector->GetFreedBytes();
const size_t duration = collector->GetDurationNs();
std::vector<uint64_t> pauses = collector->GetPauseTimes();
bool was_slow = duration > kSlowGcThreshold ||
(gc_cause == kGcCauseForAlloc && duration > kLongGcPauseThreshold);
for (size_t i = 0; i < pauses.size(); ++i) {
if (pauses[i] > kLongGcPauseThreshold) {
was_slow = true;
}
}
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 " << PrettySize(collector->GetFreedBytes()) << ", "
<< 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<base::NewTimingLogger>(collector->GetTimings());
}
}
{
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);
}
// Inform DDMS that a GC completed.
ATRACE_END();
Dbg::GcDidFinish();
return gc_type;
}
void Heap::UpdateAndMarkModUnion(collector::MarkSweep* mark_sweep, base::NewTimingLogger& timings,
collector::GcType gc_type) {
if (gc_type == collector::kGcTypeSticky) {
// Don't need to do anything for mod union table in this case since we are only scanning dirty
// cards.
return;
}
// Update zygote mod union table.
if (gc_type == collector::kGcTypePartial) {
timings.NewSplit("UpdateZygoteModUnionTable");
zygote_mod_union_table_->Update();
timings.NewSplit("ZygoteMarkReferences");
zygote_mod_union_table_->MarkReferences(mark_sweep);
}
// Processes the cards we cleared earlier and adds their objects into the mod-union table.
timings.NewSplit("UpdateModUnionTable");
image_mod_union_table_->Update();
// Scans all objects in the mod-union table.
timings.NewSplit("MarkImageToAllocSpaceReferences");
image_mod_union_table_->MarkReferences(mark_sweep);
}
static void RootMatchesObjectVisitor(const mirror::Object* root, void* arg) {
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(INFO) << "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 (obj != NULL) {
byte* card_addr = card_table->CardFromAddr(obj);
LOG(ERROR) << "Object " << obj << " references dead object " << ref << " at offset " << offset
<< "\nIsDirty = " << (*card_addr == accounting::CardTable::kCardDirty)
<< "\nObj type " << PrettyTypeOf(obj)
<< "\nRef type " << PrettyTypeOf(ref);
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";
}
// 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, VoidFunctor());
// 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);
}
if (alloc_stack->Contains(const_cast<mirror::Object*>(ref))) {
LOG(ERROR) << "Reference " << ref << " found in allocation stack!";
}
if (live_stack->Contains(const_cast<mirror::Object*>(ref))) {
LOG(ERROR) << "Reference " << ref << " found in live stack!";
}
heap_->image_mod_union_table_->Dump(LOG(ERROR) << "Image mod-union table: ");
heap_->zygote_mod_union_table_->Dump(LOG(ERROR) << "Zygote mod-union table: ");
failed_ = true;
}
}
bool IsLive(const mirror::Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
return heap_->IsLiveObjectLocked(obj);
}
static void VerifyRoots(const mirror::Object* root, void* arg) {
VerifyReferenceVisitor* visitor = reinterpret_cast<VerifyReferenceVisitor*>(arg);
(*visitor)(NULL, root, MemberOffset(0), true);
}
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()(const 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_);
collector::MarkSweep::VisitObjectReferences(obj, visitor);
failed_ = failed_ || visitor.Failed();
}
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();
// Perform the verification.
VerifyObjectVisitor visitor(this);
Runtime::Current()->VisitRoots(VerifyReferenceVisitor::VerifyRoots, &visitor, false, false);
GetLiveBitmap()->Visit(visitor);
// We don't want to verify the objects in the allocation stack since they themselves may be
// pointing to dead objects if they are not reachable.
if (visitor.Failed()) {
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->Contains(const_cast<mirror::Object*>(ref))) {
if (live_stack->Contains(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::Field>* fields = is_static ? klass->GetSFields()
: klass->GetIFields();
CHECK(fields != NULL);
for (int32_t i = 0; i < fields->GetLength(); ++i) {
const mirror::Field* 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()(const mirror::Object* obj) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_, Locks::heap_bitmap_lock_) {
VerifyReferenceCardVisitor visitor(heap_, const_cast<bool*>(&failed_));
collector::MarkSweep::VisitObjectReferences(obj, visitor);
}
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_);
// Sort the live stack so that we can quickly binary search it later.
if (verify_object_mode_ > kNoHeapVerification) {
live_stack_->Sort();
}
}
void Heap::ProcessCards(base::NewTimingLogger& timings) {
// Clear cards and keep track of cards cleared in the mod-union table.
typedef std::vector<space::ContinuousSpace*>::iterator It;
for (It it = continuous_spaces_.begin(), end = continuous_spaces_.end(); it != end; ++it) {
space::ContinuousSpace* space = *it;
if (space->IsImageSpace()) {
timings.NewSplit("ModUnionClearCards");
image_mod_union_table_->ClearCards(space);
} else if (space->IsZygoteSpace()) {
timings.NewSplit("ZygoteModUnionClearCards");
zygote_mod_union_table_->ClearCards(space);
} else {
// No mod union table for the AllocSpace. Age the cards so that the GC knows that these cards
// were dirty before the GC started.
timings.NewSplit("AllocSpaceClearCards");
card_table_->ModifyCardsAtomic(space->Begin(), space->End(), AgeCardVisitor(), VoidFunctor());
}
}
}
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_);
zygote_mod_union_table_->Update();
zygote_mod_union_table_->Verify();
image_mod_union_table_->Update();
image_mod_union_table_->Verify();
thread_list->ResumeAll();
}
}
void Heap::PreSweepingGcVerification(collector::GarbageCollector* gc) {
ThreadList* thread_list = Runtime::Current()->GetThreadList();
// 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);
Locks::mutator_lock_->SharedUnlock(self);
thread_list->SuspendAll();
{
WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
// Swapping bound bitmaps does nothing.
gc->SwapBitmaps();
if (!VerifyHeapReferences()) {
LOG(FATAL) << "Post " << gc->GetName() << "GC verification failed";
}
gc->SwapBitmaps();
}
thread_list->ResumeAll();
Locks::mutator_lock_->SharedLock(self);
}
}
void Heap::PostGcVerification(collector::GarbageCollector* gc) {
Thread* self = Thread::Current();
if (verify_system_weaks_) {
ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
collector::MarkSweep* mark_sweep = down_cast<collector::MarkSweep*>(gc);
mark_sweep->VerifySystemWeaks();
}
}
collector::GcType Heap::WaitForConcurrentGcToComplete(Thread* self) {
collector::GcType last_gc_type = collector::kGcTypeNone;
if (concurrent_gc_) {
ATRACE_BEGIN("GC: Wait For Concurrent");
bool do_wait;
uint64_t wait_start = NanoTime();
{
// Check if GC is running holding gc_complete_lock_.
MutexLock mu(self, *gc_complete_lock_);
do_wait = is_gc_running_;
}
if (do_wait) {
uint64_t wait_time;
// We must wait, change thread state then sleep on gc_complete_cond_;
ScopedThreadStateChange tsc(Thread::Current(), kWaitingForGcToComplete);
{
MutexLock mu(self, *gc_complete_lock_);
while (is_gc_running_) {
gc_complete_cond_->Wait(self);
}
last_gc_type = last_gc_type_;
wait_time = NanoTime() - wait_start;
total_wait_time_ += wait_time;
}
if (wait_time > kLongGcPauseThreshold) {
LOG(INFO) << "WaitForConcurrentGcToComplete blocked for " << PrettyDuration(wait_time);
}
}
ATRACE_END();
}
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;
}
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_;
}
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_);
}
}
SetIdealFootprint(target_size);
// Calculate when to perform the next ConcurrentGC.
if (concurrent_gc_) {
// 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_;
alloc_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);
}
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::ClearReferenceReferent(mirror::Object* reference) {
DCHECK(reference != NULL);
DCHECK_NE(reference_referent_offset_.Uint32Value(), 0U);
reference->SetFieldObject(reference_referent_offset_, NULL, true);
}
// Returns true if the reference object has not yet been enqueued.
bool Heap::IsEnqueuable(const mirror::Object* ref) {
DCHECK(ref != NULL);
const mirror::Object* queue =
ref->GetFieldObject<mirror::Object*>(reference_queue_offset_, false);
const mirror::Object* queue_next =
ref->GetFieldObject<mirror::Object*>(reference_queueNext_offset_, false);
return (queue != NULL) && (queue_next == NULL);
}
void Heap::EnqueueReference(mirror::Object* ref, mirror::Object** cleared_reference_list) {
DCHECK(ref != NULL);
CHECK(ref->GetFieldObject<mirror::Object*>(reference_queue_offset_, false) != NULL);
CHECK(ref->GetFieldObject<mirror::Object*>(reference_queueNext_offset_, false) == NULL);
EnqueuePendingReference(ref, cleared_reference_list);
}
void Heap::EnqueuePendingReference(mirror::Object* ref, mirror::Object** list) {
DCHECK(ref != NULL);
DCHECK(list != NULL);
// TODO: Remove this lock, use atomic stacks for storing references.
MutexLock mu(Thread::Current(), *reference_queue_lock_);
if (*list == NULL) {
ref->SetFieldObject(reference_pendingNext_offset_, ref, false);
*list = ref;
} else {
mirror::Object* head =
(*list)->GetFieldObject<mirror::Object*>(reference_pendingNext_offset_, false);
ref->SetFieldObject(reference_pendingNext_offset_, head, false);
(*list)->SetFieldObject(reference_pendingNext_offset_, ref, false);
}
}
mirror::Object* Heap::DequeuePendingReference(mirror::Object** list) {
DCHECK(list != NULL);
DCHECK(*list != NULL);
mirror::Object* head = (*list)->GetFieldObject<mirror::Object*>(reference_pendingNext_offset_,
false);
mirror::Object* ref;
// Note: the following code is thread-safe because it is only called from ProcessReferences which
// is single threaded.
if (*list == head) {
ref = *list;
*list = NULL;
} else {
mirror::Object* next = head->GetFieldObject<mirror::Object*>(reference_pendingNext_offset_,
false);
(*list)->SetFieldObject(reference_pendingNext_offset_, next, false);
ref = head;
}
ref->SetFieldObject(reference_pendingNext_offset_, NULL, false);
return ref;
}
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(mirror::Object** cleared) {
DCHECK(cleared != NULL);
if (*cleared != NULL) {
// 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));
soa.DecodeMethod(WellKnownClasses::java_lang_ref_ReferenceQueue_add)->Invoke(soa.Self(),
arg_array.GetArray(), arg_array.GetNumBytes(), &result, 'V');
}
*cleared = NULL;
}
}
void Heap::RequestConcurrentGC(Thread* self) {
// Make sure that we can do a concurrent GC.
Runtime* runtime = Runtime::Current();
DCHECK(concurrent_gc_);
if (runtime == NULL || !runtime->IsFinishedStarting() ||
!runtime->IsConcurrentGcEnabled()) {
return;
}
{
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
if (runtime->IsShuttingDown()) {
return;
}
}
if (self->IsHandlingStackOverflow()) {
return;
}
JNIEnv* env = self->GetJniEnv();
DCHECK(WellKnownClasses::java_lang_Daemons != NULL);
DCHECK(WellKnownClasses::java_lang_Daemons_requestGC != NULL);
env->CallStaticVoidMethod(WellKnownClasses::java_lang_Daemons,
WellKnownClasses::java_lang_Daemons_requestGC);
CHECK(!env->ExceptionCheck());
}
void Heap::ConcurrentGC(Thread* self) {
{
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
if (Runtime::Current()->IsShuttingDown()) {
return;
}
}
// Wait for any GCs currently running to finish.
if (WaitForConcurrentGcToComplete(self) == collector::kGcTypeNone) {
CollectGarbageInternal(next_gc_type_, kGcCauseBackground, false);
}
}
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();
float utilization =
static_cast<float>(alloc_space_->GetBytesAllocated()) / alloc_space_->Size();
if ((utilization > 0.75f) || ((ms_time - last_trim_time_ms_) < 2 * 1000)) {
// Don't bother trimming the alloc space if it's more than 75% utilized, or if a
// heap trim occurred in the last two seconds.
return;
}
Thread* self = Thread::Current();
{
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
Runtime* runtime = Runtime::Current();
if (runtime == NULL || !runtime->IsFinishedStarting() || runtime->IsShuttingDown()) {
// 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;
}
}
SchedPolicy policy;
get_sched_policy(self->GetTid(), &policy);
if (policy == SP_FOREGROUND || policy == SP_AUDIO_APP) {
// Don't trim the heap if we are a foreground or audio app.
return;
}
last_trim_time_ms_ = ms_time;
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());
}
size_t Heap::Trim() {
// Handle a requested heap trim on a thread outside of the main GC thread.
return alloc_space_->Trim();
}
} // namespace gc
} // namespace art