src/hotspot/share/gc/shared/collectedHeap.cpp

/*
 * Copyright (c) 2001, 2018, 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
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#include "precompiled.hpp"
#include "classfile/systemDictionary.hpp"
#include "gc/shared/allocTracer.hpp"
#include "gc/shared/barrierSet.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/collectedHeap.inline.hpp"
#include "gc/shared/gcLocker.inline.hpp"
#include "gc/shared/gcHeapSummary.hpp"
#include "gc/shared/gcTrace.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "gc/shared/gcWhen.hpp"
#include "gc/shared/memAllocator.hpp"
#include "gc/shared/vmGCOperations.hpp"
#include "logging/log.hpp"
#include "memory/metaspace.hpp"
#include "memory/resourceArea.hpp"
#include "oops/instanceMirrorKlass.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/init.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/threadSMR.hpp"
#include "runtime/vmThread.hpp"
#include "services/heapDumper.hpp"
#include "utilities/align.hpp"
#include "utilities/copy.hpp"

class ClassLoaderData;

#ifdef ASSERT
int CollectedHeap::_fire_out_of_memory_count = 0;
#endif

size_t CollectedHeap::_filler_array_max_size = 0;

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(CollectedHeap* 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());

  st.print_cr("{Heap %s GC invocations=%u (full %u):",
                 before ? "before" : "after",
                 heap->total_collections(),
                 heap->total_full_collections());

  heap->print_on(&st);
  st.print_cr("}");
}

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());
}

MetaspaceSummary CollectedHeap::create_metaspace_summary() {
  const MetaspaceSizes meta_space(
      MetaspaceUtils::committed_bytes(),
      MetaspaceUtils::used_bytes(),
      MetaspaceUtils::reserved_bytes());
  const MetaspaceSizes data_space(
      MetaspaceUtils::committed_bytes(Metaspace::NonClassType),
      MetaspaceUtils::used_bytes(Metaspace::NonClassType),
      MetaspaceUtils::reserved_bytes(Metaspace::NonClassType));
  const MetaspaceSizes class_space(
      MetaspaceUtils::committed_bytes(Metaspace::ClassType),
      MetaspaceUtils::used_bytes(Metaspace::ClassType),
      MetaspaceUtils::reserved_bytes(Metaspace::ClassType));

  const MetaspaceChunkFreeListSummary& ms_chunk_free_list_summary =
    MetaspaceUtils::chunk_free_list_summary(Metaspace::NonClassType);
  const MetaspaceChunkFreeListSummary& class_chunk_free_list_summary =
    MetaspaceUtils::chunk_free_list_summary(Metaspace::ClassType);

  return MetaspaceSummary(MetaspaceGC::capacity_until_GC(), meta_space, data_space, class_space,
                          ms_chunk_free_list_summary, class_chunk_free_list_summary);
}

void CollectedHeap::print_heap_before_gc() {
  Universe::print_heap_before_gc();
  if (_gc_heap_log != NULL) {
    _gc_heap_log->log_heap_before(this);
  }
}

void CollectedHeap::print_heap_after_gc() {
  Universe::print_heap_after_gc();
  if (_gc_heap_log != NULL) {
    _gc_heap_log->log_heap_after(this);
  }
}

void CollectedHeap::print_on_error(outputStream* st) const {
  st->print_cr("Heap:");
  print_extended_on(st);
  st->cr();

  BarrierSet::barrier_set()->print_on(st);
}

void CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
  const GCHeapSummary& heap_summary = create_heap_summary();
  gc_tracer->report_gc_heap_summary(when, heap_summary);

  const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
  gc_tracer->report_metaspace_summary(when, metaspace_summary);
}

void CollectedHeap::trace_heap_before_gc(const GCTracer* gc_tracer) {
  trace_heap(GCWhen::BeforeGC, gc_tracer);
}

void CollectedHeap::trace_heap_after_gc(const GCTracer* gc_tracer) {
  trace_heap(GCWhen::AfterGC, gc_tracer);
}

// WhiteBox API support for concurrent collectors.  These are the
// default implementations, for collectors which don't support this
// feature.
bool CollectedHeap::supports_concurrent_phase_control() const {
  return false;
}

const char* const* CollectedHeap::concurrent_phases() const {
  static const char* const result[] = { NULL };
  return result;
}

bool CollectedHeap::request_concurrent_phase(const char* phase) {
  return false;
}

bool CollectedHeap::is_oop(oop object) const {
  if (!check_obj_alignment(object)) {
    return false;
  }

  if (!is_in_reserved(object)) {
    return false;
  }

  if (is_in_reserved(object->klass_or_null())) {
    return false;
  }

  return true;
}

// Memory state functions.


CollectedHeap::CollectedHeap() :
  _is_gc_active(false),
  _total_collections(0),
  _total_full_collections(0),
  _gc_cause(GCCause::_no_gc),
  _gc_lastcause(GCCause::_no_gc)
{
  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);

  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);
  }

  // Create the ring log
  if (LogEvents) {
    _gc_heap_log = new GCHeapLog();
  } else {
    _gc_heap_log = NULL;
  }
}

// This interface assumes that it's being called by the
// vm thread. It collects the heap assuming that the
// heap lock is already held and that we are executing in
// the context of the vm thread.
void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
  assert(Thread::current()->is_VM_thread(), "Precondition#1");
  assert(Heap_lock->is_locked(), "Precondition#2");
  GCCauseSetter gcs(this, cause);
  switch (cause) {
    case GCCause::_heap_inspection:
    case GCCause::_heap_dump:
    case GCCause::_metadata_GC_threshold : {
      HandleMark hm;
      do_full_collection(false);        // don't clear all soft refs
      break;
    }
    case GCCause::_metadata_GC_clear_soft_refs: {
      HandleMark hm;
      do_full_collection(true);         // do clear all soft refs
      break;
    }
    default:
      ShouldNotReachHere(); // Unexpected use of this function
  }
}

MetaWord* CollectedHeap::satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
                                                            size_t word_size,
                                                            Metaspace::MetadataType mdtype) {
  uint loop_count = 0;
  uint gc_count = 0;
  uint full_gc_count = 0;

  assert(!Heap_lock->owned_by_self(), "Should not be holding the Heap_lock");

  do {
    MetaWord* result = loader_data->metaspace_non_null()->allocate(word_size, mdtype);
    if (result != NULL) {
      return result;
    }

    if (GCLocker::is_active_and_needs_gc()) {
      // If the GCLocker is active, just expand and allocate.
      // If that does not succeed, wait if this thread is not
      // in a critical section itself.
      result = loader_data->metaspace_non_null()->expand_and_allocate(word_size, mdtype);
      if (result != NULL) {
        return result;
      }
      JavaThread* jthr = JavaThread::current();
      if (!jthr->in_critical()) {
        // Wait for JNI critical section to be exited
        GCLocker::stall_until_clear();
        // The GC invoked by the last thread leaving the critical
        // section will be a young collection and a full collection
        // is (currently) needed for unloading classes so continue
        // to the next iteration to get a full GC.
        continue;
      } else {
        if (CheckJNICalls) {
          fatal("Possible deadlock due to allocating while"
                " in jni critical section");
        }
        return NULL;
      }
    }

    {  // Need lock to get self consistent gc_count's
      MutexLocker ml(Heap_lock);
      gc_count      = Universe::heap()->total_collections();
      full_gc_count = Universe::heap()->total_full_collections();
    }

    // Generate a VM operation
    VM_CollectForMetadataAllocation op(loader_data,
                                       word_size,
                                       mdtype,
                                       gc_count,
                                       full_gc_count,
                                       GCCause::_metadata_GC_threshold);
    VMThread::execute(&op);

    // If GC was locked out, try again. Check before checking success because the
    // prologue could have succeeded and the GC still have been locked out.
    if (op.gc_locked()) {
      continue;
    }

    if (op.prologue_succeeded()) {
      return op.result();
    }
    loop_count++;
    if ((QueuedAllocationWarningCount > 0) &&
        (loop_count % QueuedAllocationWarningCount == 0)) {
      log_warning(gc, ergo)("satisfy_failed_metadata_allocation() retries %d times,"
                            " size=" SIZE_FORMAT, loop_count, word_size);
    }
  } while (true);  // Until a GC is done
}

#ifndef PRODUCT
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

size_t CollectedHeap::max_tlab_size() const {
  // TLABs can't be bigger than we can fill with a int[Integer.MAX_VALUE].
  // This restriction could be removed by enabling filling with multiple arrays.
  // If we compute that the reasonable way as
  //    header_size + ((sizeof(jint) * max_jint) / HeapWordSize)
  // we'll overflow on the multiply, so we do the divide first.
  // We actually lose a little by dividing first,
  // but that just makes the TLAB  somewhat smaller than the biggest array,
  // which is fine, since we'll be able to fill that.
  size_t max_int_size = typeArrayOopDesc::header_size(T_INT) +
              sizeof(jint) *
              ((juint) max_jint / (size_t) HeapWordSize);
  return align_down(max_int_size, MinObjAlignment);
}

size_t CollectedHeap::filler_array_hdr_size() {
  return 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(is_object_aligned(words), "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, "size too large " SIZE_FORMAT " becomes %d", words, (int)len);

  ObjArrayAllocator allocator(Universe::intArrayKlassObj(), words, (int)len, /* do_zero */ false);
  allocator.initialize(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");
    ObjAllocator allocator(SystemDictionary::Object_klass(), words);
    allocator.initialize(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.

  // Multiple objects may be required depending on the filler array maximum size. Fill
  // the range up to that with objects that are filler_array_max_size sized. 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;
  }

  fill_with_object_impl(start, words, zap);
}

void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
  CollectedHeap::fill_with_object(start, end, zap);
}

HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
                                           size_t requested_size,
                                           size_t* actual_size) {
  guarantee(false, "thread-local allocation buffers not supported");
  return NULL;
}

oop CollectedHeap::obj_allocate(Klass* klass, int size, TRAPS) {
  ObjAllocator allocator(klass, size, THREAD);
  return allocator.allocate();
}

oop CollectedHeap::array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS) {
  ObjArrayAllocator allocator(klass, size, length, do_zero, THREAD);
  return allocator.allocate();
}

oop CollectedHeap::class_allocate(Klass* klass, int size, TRAPS) {
  ClassAllocator allocator(klass, size, THREAD);
  return allocator.allocate();
}

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;
  // The main thread starts allocating via a TLAB even before it
  // has added itself to the threads list at vm boot-up.
  JavaThreadIteratorWithHandle jtiwh;
  assert(!use_tlab || jtiwh.length() > 0,
         "Attempt to fill tlabs before main thread has been added"
         " to threads list is doomed to failure!");
  BarrierSet *bs = BarrierSet::barrier_set();
  for (; JavaThread *thread = jtiwh.next(); ) {
     if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
     bs->make_parsable(thread);
  }
}

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::full_gc_dump(GCTimer* timer, bool before) {
  assert(timer != NULL, "timer is null");
  if ((HeapDumpBeforeFullGC && before) || (HeapDumpAfterFullGC && !before)) {
    GCTraceTime(Info, gc) tm(before ? "Heap Dump (before full gc)" : "Heap Dump (after full gc)", timer);
    HeapDumper::dump_heap();
  }

  LogTarget(Trace, gc, classhisto) lt;
  if (lt.is_enabled()) {
    GCTraceTime(Trace, gc, classhisto) tm(before ? "Class Histogram (before full gc)" : "Class Histogram (after full gc)", timer);
    ResourceMark rm;
    LogStream ls(lt);
    VM_GC_HeapInspection inspector(&ls, false /* ! full gc */);
    inspector.doit();
  }
}

void CollectedHeap::pre_full_gc_dump(GCTimer* timer) {
  full_gc_dump(timer, true);
}

void CollectedHeap::post_full_gc_dump(GCTimer* timer) {
  full_gc_dump(timer, false);
}

void CollectedHeap::initialize_reserved_region(HeapWord *start, HeapWord *end) {
  // It is important to do this in a way such that concurrent readers can't
  // temporarily think something is in the heap.  (Seen this happen in asserts.)
  _reserved.set_word_size(0);
  _reserved.set_start(start);
  _reserved.set_end(end);
}

void CollectedHeap::post_initialize() {
  initialize_serviceability();
}

#ifndef PRODUCT

bool CollectedHeap::promotion_should_fail(volatile size_t* count) {
  // Access to count is not atomic; the value does not have to be exact.
  if (PromotionFailureALot) {
    const size_t gc_num = total_collections();
    const size_t elapsed_gcs = gc_num - _promotion_failure_alot_gc_number;
    if (elapsed_gcs >= PromotionFailureALotInterval) {
      // Test for unsigned arithmetic wrap-around.
      if (++*count >= PromotionFailureALotCount) {
        *count = 0;
        return true;
      }
    }
  }
  return false;
}

bool CollectedHeap::promotion_should_fail() {
  return promotion_should_fail(&_promotion_failure_alot_count);
}

void CollectedHeap::reset_promotion_should_fail(volatile size_t* count) {
  if (PromotionFailureALot) {
    _promotion_failure_alot_gc_number = total_collections();
    *count = 0;
  }
}

void CollectedHeap::reset_promotion_should_fail() {
  reset_promotion_should_fail(&_promotion_failure_alot_count);
}

#endif  // #ifndef PRODUCT

bool CollectedHeap::supports_object_pinning() const {
  return false;
}

oop CollectedHeap::pin_object(JavaThread* thread, oop obj) {
  ShouldNotReachHere();
  return NULL;
}

void CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
  ShouldNotReachHere();
}

void CollectedHeap::deduplicate_string(oop str) {
  // Do nothing, unless overridden in subclass.
}