/*
* Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/systemDictionary.hpp"
#include "gc_implementation/shared/gcHeapSummary.hpp"
#include "gc_implementation/shared/gcTrace.hpp"
#include "gc_implementation/shared/gcTraceTime.hpp"
#include "gc_implementation/shared/gcWhen.hpp"
#include "gc_implementation/shared/vmGCOperations.hpp"
#include "gc_interface/allocTracer.hpp"
#include "gc_interface/collectedHeap.hpp"
#include "gc_interface/collectedHeap.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/instanceMirrorKlass.hpp"
#include "runtime/init.hpp"
#include "services/heapDumper.hpp"
#ifdef TARGET_OS_FAMILY_linux
# include "thread_linux.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_solaris
# include "thread_solaris.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_windows
# include "thread_windows.inline.hpp"
#endif
#ifdef TARGET_OS_FAMILY_bsd
# include "thread_bsd.inline.hpp"
#endif
#ifdef ASSERT
int CollectedHeap::_fire_out_of_memory_count = 0;
#endif
size_t CollectedHeap::_filler_array_max_size = 0;
const char* CollectedHeap::OverflowMessage
= "The size of the object heap + perm gen exceeds the maximum representable size";
template <>
void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
st->print_cr("GC heap %s", m.is_before ? "before" : "after");
st->print_raw(m);
}
void GCHeapLog::log_heap(bool before) {
if (!should_log()) {
return;
}
double timestamp = fetch_timestamp();
MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
int index = compute_log_index();
_records[index].thread = NULL; // Its the GC thread so it's not that interesting.
_records[index].timestamp = timestamp;
_records[index].data.is_before = before;
stringStream st(_records[index].data.buffer(), _records[index].data.size());
if (before) {
Universe::print_heap_before_gc(&st, true);
} else {
Universe::print_heap_after_gc(&st, true);
}
}
VirtualSpaceSummary CollectedHeap::create_heap_space_summary() {
size_t capacity_in_words = capacity() / HeapWordSize;
return VirtualSpaceSummary(
reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end());
}
GCHeapSummary CollectedHeap::create_heap_summary() {
VirtualSpaceSummary heap_space = create_heap_space_summary();
return GCHeapSummary(heap_space, used());
}
PermGenSummary CollectedHeap::create_perm_gen_summary() {
VirtualSpaceSummary perm_space = create_perm_gen_space_summary();
SpaceSummary object_space(perm_space.start(), perm_space.committed_end(), permanent_used());
return PermGenSummary(perm_space, object_space);
}
void CollectedHeap::print_heap_before_gc() {
if (PrintHeapAtGC) {
Universe::print_heap_before_gc();
}
if (_gc_heap_log != NULL) {
_gc_heap_log->log_heap_before();
}
}
void CollectedHeap::print_heap_after_gc() {
if (PrintHeapAtGC) {
Universe::print_heap_after_gc();
}
if (_gc_heap_log != NULL) {
_gc_heap_log->log_heap_after();
}
}
void CollectedHeap::trace_heap(GCWhen::Type when, GCTracer* gc_tracer) {
const GCHeapSummary& heap_summary = create_heap_summary();
const PermGenSummary& perm_summary = create_perm_gen_summary();
gc_tracer->report_gc_heap_summary(when, heap_summary, perm_summary);
}
void CollectedHeap::trace_heap_before_gc(GCTracer* gc_tracer) {
trace_heap(GCWhen::BeforeGC, gc_tracer);
}
void CollectedHeap::trace_heap_after_gc(GCTracer* gc_tracer) {
trace_heap(GCWhen::AfterGC, gc_tracer);
}
// Memory state functions.
CollectedHeap::CollectedHeap() : _n_par_threads(0)
{
const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
const size_t elements_per_word = HeapWordSize / sizeof(jint);
_filler_array_max_size = align_object_size(filler_array_hdr_size() +
max_len / elements_per_word);
_barrier_set = NULL;
_is_gc_active = false;
_total_collections = _total_full_collections = 0;
_gc_cause = _gc_lastcause = GCCause::_no_gc;
NOT_PRODUCT(_promotion_failure_alot_count = 0;)
NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
if (UsePerfData) {
EXCEPTION_MARK;
// create the gc cause jvmstat counters
_perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
80, GCCause::to_string(_gc_cause), CHECK);
_perf_gc_lastcause =
PerfDataManager::create_string_variable(SUN_GC, "lastCause",
80, GCCause::to_string(_gc_lastcause), CHECK);
}
_defer_initial_card_mark = false; // strengthened by subclass in pre_initialize() below.
// Create the ring log
if (LogEvents) {
_gc_heap_log = new GCHeapLog();
} else {
_gc_heap_log = NULL;
}
}
void CollectedHeap::pre_initialize() {
// Used for ReduceInitialCardMarks (when COMPILER2 is used);
// otherwise remains unused.
#ifdef COMPILER2
_defer_initial_card_mark = ReduceInitialCardMarks && can_elide_tlab_store_barriers()
&& (DeferInitialCardMark || card_mark_must_follow_store());
#else
assert(_defer_initial_card_mark == false, "Who would set it?");
#endif
}
size_t CollectedHeap::add_and_check_overflow(size_t total, size_t size) {
assert(size >= 0, "must be");
size_t result = total + size;
if (result < size) {
// We must have overflowed
vm_exit_during_initialization(CollectedHeap::OverflowMessage);
}
return result;
}
size_t CollectedHeap::round_up_and_check_overflow(size_t total, size_t size) {
assert(size >= 0, "must be");
size_t result = round_to(total, size);
if (result < size) {
// We must have overflowed
vm_exit_during_initialization(CollectedHeap::OverflowMessage);
}
return result;
}
#ifndef PRODUCT
void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
if (CheckMemoryInitialization && ZapUnusedHeapArea) {
for (size_t slot = 0; slot < size; slot += 1) {
assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
"Found badHeapWordValue in post-allocation check");
}
}
}
void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
if (CheckMemoryInitialization && ZapUnusedHeapArea) {
for (size_t slot = 0; slot < size; slot += 1) {
assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
"Found non badHeapWordValue in pre-allocation check");
}
}
}
#endif // PRODUCT
#ifdef ASSERT
void CollectedHeap::check_for_valid_allocation_state() {
Thread *thread = Thread::current();
// How to choose between a pending exception and a potential
// OutOfMemoryError? Don't allow pending exceptions.
// This is a VM policy failure, so how do we exhaustively test it?
assert(!thread->has_pending_exception(),
"shouldn't be allocating with pending exception");
if (StrictSafepointChecks) {
assert(thread->allow_allocation(),
"Allocation done by thread for which allocation is blocked "
"by No_Allocation_Verifier!");
// Allocation of an oop can always invoke a safepoint,
// hence, the true argument
thread->check_for_valid_safepoint_state(true);
}
}
#endif
HeapWord* CollectedHeap::allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size) {
// Retain tlab and allocate object in shared space if
// the amount free in the tlab is too large to discard.
if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {
thread->tlab().record_slow_allocation(size);
return NULL;
}
// Discard tlab and allocate a new one.
// To minimize fragmentation, the last TLAB may be smaller than the rest.
size_t new_tlab_size = thread->tlab().compute_size(size);
thread->tlab().clear_before_allocation();
if (new_tlab_size == 0) {
return NULL;
}
// Allocate a new TLAB...
HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);
if (obj == NULL) {
return NULL;
}
AllocTracer::send_allocation_in_new_tlab_event(klass, new_tlab_size * HeapWordSize, size * HeapWordSize);
if (ZeroTLAB) {
// ..and clear it.
Copy::zero_to_words(obj, new_tlab_size);
} else {
// ...and zap just allocated object.
#ifdef ASSERT
// Skip mangling the space corresponding to the object header to
// ensure that the returned space is not considered parsable by
// any concurrent GC thread.
size_t hdr_size = oopDesc::header_size();
Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal);
#endif // ASSERT
}
thread->tlab().fill(obj, obj + size, new_tlab_size);
return obj;
}
void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
MemRegion deferred = thread->deferred_card_mark();
if (!deferred.is_empty()) {
assert(_defer_initial_card_mark, "Otherwise should be empty");
{
// Verify that the storage points to a parsable object in heap
DEBUG_ONLY(oop old_obj = oop(deferred.start());)
assert(is_in(old_obj), "Not in allocated heap");
assert(!can_elide_initializing_store_barrier(old_obj),
"Else should have been filtered in new_store_pre_barrier()");
assert(!is_in_permanent(old_obj), "Sanity: not expected");
assert(old_obj->is_oop(true), "Not an oop");
assert(old_obj->is_parsable(), "Will not be concurrently parsable");
assert(deferred.word_size() == (size_t)(old_obj->size()),
"Mismatch: multiple objects?");
}
BarrierSet* bs = barrier_set();
assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");
bs->write_region(deferred);
// "Clear" the deferred_card_mark field
thread->set_deferred_card_mark(MemRegion());
}
assert(thread->deferred_card_mark().is_empty(), "invariant");
}
// Helper for ReduceInitialCardMarks. For performance,
// compiled code may elide card-marks for initializing stores
// to a newly allocated object along the fast-path. We
// compensate for such elided card-marks as follows:
// (a) Generational, non-concurrent collectors, such as
// GenCollectedHeap(ParNew,DefNew,Tenured) and
// ParallelScavengeHeap(ParallelGC, ParallelOldGC)
// need the card-mark if and only if the region is
// in the old gen, and do not care if the card-mark
// succeeds or precedes the initializing stores themselves,
// so long as the card-mark is completed before the next
// scavenge. For all these cases, we can do a card mark
// at the point at which we do a slow path allocation
// in the old gen, i.e. in this call.
// (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
// in addition that the card-mark for an old gen allocated
// object strictly follow any associated initializing stores.
// In these cases, the memRegion remembered below is
// used to card-mark the entire region either just before the next
// slow-path allocation by this thread or just before the next scavenge or
// CMS-associated safepoint, whichever of these events happens first.
// (The implicit assumption is that the object has been fully
// initialized by this point, a fact that we assert when doing the
// card-mark.)
// (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
// G1 concurrent marking is in progress an SATB (pre-write-)barrier is
// is used to remember the pre-value of any store. Initializing
// stores will not need this barrier, so we need not worry about
// compensating for the missing pre-barrier here. Turning now
// to the post-barrier, we note that G1 needs a RS update barrier
// which simply enqueues a (sequence of) dirty cards which may
// optionally be refined by the concurrent update threads. Note
// that this barrier need only be applied to a non-young write,
// but, like in CMS, because of the presence of concurrent refinement
// (much like CMS' precleaning), must strictly follow the oop-store.
// Thus, using the same protocol for maintaining the intended
// invariants turns out, serendepitously, to be the same for both
// G1 and CMS.
//
// For any future collector, this code should be reexamined with
// that specific collector in mind, and the documentation above suitably
// extended and updated.
oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
// If a previous card-mark was deferred, flush it now.
flush_deferred_store_barrier(thread);
if (can_elide_initializing_store_barrier(new_obj)) {
// The deferred_card_mark region should be empty
// following the flush above.
assert(thread->deferred_card_mark().is_empty(), "Error");
} else {
MemRegion mr((HeapWord*)new_obj, new_obj->size());
assert(!mr.is_empty(), "Error");
if (_defer_initial_card_mark) {
// Defer the card mark
thread->set_deferred_card_mark(mr);
} else {
// Do the card mark
BarrierSet* bs = barrier_set();
assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");
bs->write_region(mr);
}
}
return new_obj;
}
size_t CollectedHeap::filler_array_hdr_size() {
return size_t(align_object_offset(arrayOopDesc::header_size(T_INT))); // align to Long
}
size_t CollectedHeap::filler_array_min_size() {
return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
}
#ifdef ASSERT
void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
{
assert(words >= min_fill_size(), "too small to fill");
assert(words % MinObjAlignment == 0, "unaligned size");
assert(Universe::heap()->is_in_reserved(start), "not in heap");
assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");
}
void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
{
if (ZapFillerObjects && zap) {
Copy::fill_to_words(start + filler_array_hdr_size(),
words - filler_array_hdr_size(), 0XDEAFBABE);
}
}
#endif // ASSERT
void
CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
{
assert(words >= filler_array_min_size(), "too small for an array");
assert(words <= filler_array_max_size(), "too big for a single object");
const size_t payload_size = words - filler_array_hdr_size();
const size_t len = payload_size * HeapWordSize / sizeof(jint);
assert((int)len >= 0, err_msg("size too large " SIZE_FORMAT " becomes %d", words, (int)len));
// Set the length first for concurrent GC.
((arrayOop)start)->set_length((int)len);
post_allocation_setup_common(Universe::intArrayKlassObj(), start);
DEBUG_ONLY(zap_filler_array(start, words, zap);)
}
void
CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
{
assert(words <= filler_array_max_size(), "too big for a single object");
if (words >= filler_array_min_size()) {
fill_with_array(start, words, zap);
} else if (words > 0) {
assert(words == min_fill_size(), "unaligned size");
post_allocation_setup_common(SystemDictionary::Object_klass(), start);
}
}
void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
{
DEBUG_ONLY(fill_args_check(start, words);)
HandleMark hm; // Free handles before leaving.
fill_with_object_impl(start, words, zap);
}
void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
{
DEBUG_ONLY(fill_args_check(start, words);)
HandleMark hm; // Free handles before leaving.
#ifdef _LP64
// A single array can fill ~8G, so multiple objects are needed only in 64-bit.
// First fill with arrays, ensuring that any remaining space is big enough to
// fill. The remainder is filled with a single object.
const size_t min = min_fill_size();
const size_t max = filler_array_max_size();
while (words > max) {
const size_t cur = words - max >= min ? max : max - min;
fill_with_array(start, cur, zap);
start += cur;
words -= cur;
}
#endif
fill_with_object_impl(start, words, zap);
}
HeapWord* CollectedHeap::allocate_new_tlab(size_t size) {
guarantee(false, "thread-local allocation buffers not supported");
return NULL;
}
void CollectedHeap::ensure_parsability(bool retire_tlabs) {
// The second disjunct in the assertion below makes a concession
// for the start-up verification done while the VM is being
// created. Callers be careful that you know that mutators
// aren't going to interfere -- for instance, this is permissible
// if we are still single-threaded and have either not yet
// started allocating (nothing much to verify) or we have
// started allocating but are now a full-fledged JavaThread
// (and have thus made our TLAB's) available for filling.
assert(SafepointSynchronize::is_at_safepoint() ||
!is_init_completed(),
"Should only be called at a safepoint or at start-up"
" otherwise concurrent mutator activity may make heap "
" unparsable again");
const bool use_tlab = UseTLAB;
const bool deferred = _defer_initial_card_mark;
// The main thread starts allocating via a TLAB even before it
// has added itself to the threads list at vm boot-up.
assert(!use_tlab || Threads::first() != NULL,
"Attempt to fill tlabs before main thread has been added"
" to threads list is doomed to failure!");
for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
#ifdef COMPILER2
// The deferred store barriers must all have been flushed to the
// card-table (or other remembered set structure) before GC starts
// processing the card-table (or other remembered set).
if (deferred) flush_deferred_store_barrier(thread);
#else
assert(!deferred, "Should be false");
assert(thread->deferred_card_mark().is_empty(), "Should be empty");
#endif
}
}
void CollectedHeap::accumulate_statistics_all_tlabs() {
if (UseTLAB) {
assert(SafepointSynchronize::is_at_safepoint() ||
!is_init_completed(),
"should only accumulate statistics on tlabs at safepoint");
ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
}
}
void CollectedHeap::resize_all_tlabs() {
if (UseTLAB) {
assert(SafepointSynchronize::is_at_safepoint() ||
!is_init_completed(),
"should only resize tlabs at safepoint");
ThreadLocalAllocBuffer::resize_all_tlabs();
}
}
void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
if (HeapDumpBeforeFullGC) {
GCTraceTime tt("Heap Dump (before full gc): ", PrintGCDetails, false, timer);
// We are doing a "major" collection and a heap dump before
// major collection has been requested.
HeapDumper::dump_heap();
}
if (PrintClassHistogramBeforeFullGC) {
GCTraceTime tt("Class Histogram (before full gc): ", PrintGCDetails, true, timer);
VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);
inspector.doit();
}
}
void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
if (HeapDumpAfterFullGC) {
GCTraceTime tt("Heap Dump (after full gc): ", PrintGCDetails, false, timer);
HeapDumper::dump_heap();
}
if (PrintClassHistogramAfterFullGC) {
GCTraceTime tt("Class Histogram (after full gc): ", PrintGCDetails, true, timer);
VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);
inspector.doit();
}
}
oop CollectedHeap::Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS) {
debug_only(check_for_valid_allocation_state());
assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");
assert(size >= 0, "int won't convert to size_t");
HeapWord* obj;
if (JavaObjectsInPerm) {
obj = common_permanent_mem_allocate_init(size, CHECK_NULL);
} else {
assert(ScavengeRootsInCode > 0, "must be");
obj = common_mem_allocate_init(real_klass, size, CHECK_NULL);
}
post_allocation_setup_common(klass, obj);
assert(Universe::is_bootstrapping() ||
!((oop)obj)->blueprint()->oop_is_array(), "must not be an array");
NOT_PRODUCT(Universe::heap()->check_for_bad_heap_word_value(obj, size));
oop mirror = (oop)obj;
java_lang_Class::set_oop_size(mirror, size);
// Setup indirections
if (!real_klass.is_null()) {
java_lang_Class::set_klass(mirror, real_klass());
real_klass->set_java_mirror(mirror);
}
instanceMirrorKlass* mk = instanceMirrorKlass::cast(mirror->klass());
assert(size == mk->instance_size(real_klass), "should have been set");
// notify jvmti and dtrace
post_allocation_notify(klass, (oop)obj);
return mirror;
}
/////////////// Unit tests ///////////////
#ifndef PRODUCT
void CollectedHeap::test_is_in() {
CollectedHeap* heap = Universe::heap();
uintptr_t epsilon = (uintptr_t) MinObjAlignment;
uintptr_t heap_start = (uintptr_t) heap->_reserved.start();
uintptr_t heap_end = (uintptr_t) heap->_reserved.end();
// Test that NULL is not in the heap.
assert(!heap->is_in(NULL), "NULL is unexpectedly in the heap");
// Test that a pointer to before the heap start is reported as outside the heap.
assert(heap_start >= ((uintptr_t)NULL + epsilon), "sanity");
void* before_heap = (void*)(heap_start - epsilon);
assert(!heap->is_in(before_heap),
err_msg("before_heap: " PTR_FORMAT " is unexpectedly in the heap", before_heap));
// Test that a pointer to after the heap end is reported as outside the heap.
assert(heap_end <= ((uintptr_t)-1 - epsilon), "sanity");
void* after_heap = (void*)(heap_end + epsilon);
assert(!heap->is_in(after_heap),
err_msg("after_heap: " PTR_FORMAT " is unexpectedly in the heap", after_heap));
}
#endif