C++ GenCollectedHeap::gc_cause方法代码示例

//////////////////////////////////////////////////////////
// Methods in class VM_CMS_Final_Remark_Operation
//////////////////////////////////////////////////////////
void VM_CMS_Final_Remark::doit() {
  if (lost_race()) {
    // Nothing to do.
    return;
  }
#ifndef USDT2
  HS_DTRACE_PROBE(hs_private, cms__remark__begin);
#else /* USDT2 */
  HS_PRIVATE_CMS_REMARK_BEGIN();
#endif /* USDT2 */

  _collector->_gc_timer_cm->register_gc_pause_start("Final Mark");

  GenCollectedHeap* gch = GenCollectedHeap::heap();
  GCCauseSetter gccs(gch, GCCause::_cms_final_remark);

  VM_CMS_Operation::verify_before_gc();

  IsGCActiveMark x; // stop-world GC active
  _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, gch->gc_cause());

  VM_CMS_Operation::verify_after_gc();

  _collector->save_heap_summary();
  _collector->_gc_timer_cm->register_gc_pause_end();

#ifndef USDT2
  HS_DTRACE_PROBE(hs_private, cms__remark__end);
#else /* USDT2 */
  HS_PRIVATE_CMS_REMARK_END();
#endif /* USDT2 */
}

void OneContigSpaceCardGeneration::collect(bool   full,
                                           bool   clear_all_soft_refs,
                                           size_t size,
                                           bool   is_tlab) {
  GenCollectedHeap* gch = GenCollectedHeap::heap();

  SpecializationStats::clear();
  // Temporarily expand the span of our ref processor, so
  // refs discovery is over the entire heap, not just this generation
  ReferenceProcessorSpanMutator
    x(ref_processor(), gch->reserved_region());

  STWGCTimer* gc_timer = GenMarkSweep::gc_timer();
  gc_timer->register_gc_start(os::elapsed_counter());

  SerialOldTracer* gc_tracer = GenMarkSweep::gc_tracer();
  gc_tracer->report_gc_start(gch->gc_cause(), gc_timer->gc_start());

  GenMarkSweep::invoke_at_safepoint(_level, ref_processor(), clear_all_soft_refs);

  gc_timer->register_gc_end(os::elapsed_counter());

  gc_tracer->report_gc_end(os::elapsed_counter(), gc_timer->time_partitions());

  SpecializationStats::print();
}

//////////////////////////////////////////////////////////
// Methods in class VM_CMS_Final_Remark_Operation
//////////////////////////////////////////////////////////
void VM_CMS_Final_Remark::doit() {
  if (lost_race()) {
    // Nothing to do.
    return;
  }
  HS_PRIVATE_CMS_REMARK_BEGIN();
  GCIdMark gc_id_mark(_gc_id);

  _collector->_gc_timer_cm->register_gc_pause_start("Final Mark");

  GenCollectedHeap* gch = GenCollectedHeap::heap();
  GCCauseSetter gccs(gch, GCCause::_cms_final_remark);

  VM_CMS_Operation::verify_before_gc();

  IsGCActiveMark x; // stop-world GC active
  _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, gch->gc_cause());

  VM_CMS_Operation::verify_after_gc();

  _collector->save_heap_summary();
  _collector->_gc_timer_cm->register_gc_pause_end();

  HS_PRIVATE_CMS_REMARK_END();
}

void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,
  bool clear_all_softrefs) {
  assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");

  GenCollectedHeap* gch = GenCollectedHeap::heap();
#ifdef ASSERT
  if (gch->collector_policy()->should_clear_all_soft_refs()) {
    assert(clear_all_softrefs, "Policy should have been checked earlier");
  }
#endif

  // hook up weak ref data so it can be used during Mark-Sweep
  assert(ref_processor() == NULL, "no stomping");
  assert(rp != NULL, "should be non-NULL");
  _ref_processor = rp;
  rp->setup_policy(clear_all_softrefs);

  TraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, gclog_or_tty);

  // When collecting the permanent generation methodOops may be moving,
  // so we either have to flush all bcp data or convert it into bci.
  CodeCache::gc_prologue();
  Threads::gc_prologue();

  // Increment the invocation count for the permanent generation, since it is
  // implicitly collected whenever we do a full mark sweep collection.
  gch->perm_gen()->stat_record()->invocations++;

  // Capture heap size before collection for printing.
  size_t gch_prev_used = gch->used();

  // Some of the card table updates below assume that the perm gen is
  // also being collected.
  assert(level == gch->n_gens() - 1,
         "All generations are being collected, ergo perm gen too.");

  // Capture used regions for each generation that will be
  // subject to collection, so that card table adjustments can
  // be made intelligently (see clear / invalidate further below).
  gch->save_used_regions(level, true /* perm */);

  allocate_stacks();

  mark_sweep_phase1(level, clear_all_softrefs);

  mark_sweep_phase2();

  // Don't add any more derived pointers during phase3
  COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
  COMPILER2_PRESENT(DerivedPointerTable::set_active(false));

  mark_sweep_phase3(level);

  VALIDATE_MARK_SWEEP_ONLY(
    if (ValidateMarkSweep) {
      guarantee(_root_refs_stack->length() == 0, "should be empty by now");
    }
  )

void DefNewGeneration::collect(bool   full,
                               bool   clear_all_soft_refs,
                               size_t size,
                               bool   is_tlab) {
  assert(full || size > 0, "otherwise we don't want to collect");

  GenCollectedHeap* gch = GenCollectedHeap::heap();

  _gc_timer->register_gc_start();
  DefNewTracer gc_tracer;
  gc_tracer.report_gc_start(gch->gc_cause(), _gc_timer->gc_start());

  _next_gen = gch->next_gen(this);

  // If the next generation is too full to accommodate promotion
  // from this generation, pass on collection; let the next generation
  // do it.
  if (!collection_attempt_is_safe()) {
    if (Verbose && PrintGCDetails) {
      gclog_or_tty->print(" :: Collection attempt not safe :: ");
    }
    gch->set_incremental_collection_failed(); // Slight lie: we did not even attempt one
    return;
  }
  assert(to()->is_empty(), "Else not collection_attempt_is_safe");

  init_assuming_no_promotion_failure();

  GCTraceTime t1(GCCauseString("GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL);
  // Capture heap used before collection (for printing).
  size_t gch_prev_used = gch->used();

  gch->trace_heap_before_gc(&gc_tracer);

  SpecializationStats::clear();

  // These can be shared for all code paths
  IsAliveClosure is_alive(this);
  ScanWeakRefClosure scan_weak_ref(this);

  age_table()->clear();
  to()->clear(SpaceDecorator::Mangle);

  gch->rem_set()->prepare_for_younger_refs_iterate(false);

  assert(gch->no_allocs_since_save_marks(0),
         "save marks have not been newly set.");

  // Not very pretty.
  CollectorPolicy* cp = gch->collector_policy();

  FastScanClosure fsc_with_no_gc_barrier(this, false);
  FastScanClosure fsc_with_gc_barrier(this, true);

  KlassScanClosure klass_scan_closure(&fsc_with_no_gc_barrier,
                                      gch->rem_set()->klass_rem_set());

  set_promo_failure_scan_stack_closure(&fsc_with_no_gc_barrier);
  FastEvacuateFollowersClosure evacuate_followers(gch, _level, this,
                                                  &fsc_with_no_gc_barrier,
                                                  &fsc_with_gc_barrier);

  assert(gch->no_allocs_since_save_marks(0),
         "save marks have not been newly set.");

  int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;

  gch->gen_process_strong_roots(_level,
                                true,  // Process younger gens, if any,
                                       // as strong roots.
                                true,  // activate StrongRootsScope
                                true,  // is scavenging
                                SharedHeap::ScanningOption(so),
                                &fsc_with_no_gc_barrier,
                                true,   // walk *all* scavengable nmethods
                                &fsc_with_gc_barrier,
                                &klass_scan_closure);

  // "evacuate followers".
  evacuate_followers.do_void();

  FastKeepAliveClosure keep_alive(this, &scan_weak_ref);
  ReferenceProcessor* rp = ref_processor();
  rp->setup_policy(clear_all_soft_refs);
  const ReferenceProcessorStats& stats =
  rp->process_discovered_references(&is_alive, &keep_alive, &evacuate_followers,
                                    NULL, _gc_timer);
  gc_tracer.report_gc_reference_stats(stats);

  if (!_promotion_failed) {
    // Swap the survivor spaces.
    eden()->clear(SpaceDecorator::Mangle);
    from()->clear(SpaceDecorator::Mangle);
    if (ZapUnusedHeapArea) {
      // This is now done here because of the piece-meal mangling which
      // can check for valid mangling at intermediate points in the
      // collection(s).  When a minor collection fails to collect
      // sufficient space resizing of the young generation can occur
      // an redistribute the spaces in the young generation.  Mangle
      // here so that unzapped regions don't get distributed to
//.........这里部分代码省略.........

void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp, bool clear_all_softrefs) {
  guarantee(level == 1, "We always collect both old and young.");
  assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");

  GenCollectedHeap* gch = GenCollectedHeap::heap();
#ifdef ASSERT
  if (gch->collector_policy()->should_clear_all_soft_refs()) {
    assert(clear_all_softrefs, "Policy should have been checked earlier");
  }
#endif

  // hook up weak ref data so it can be used during Mark-Sweep
  assert(ref_processor() == NULL, "no stomping");
  assert(rp != NULL, "should be non-NULL");
  _ref_processor = rp;
  rp->setup_policy(clear_all_softrefs);

  GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL, _gc_tracer->gc_id());

  gch->trace_heap_before_gc(_gc_tracer);

  // When collecting the permanent generation Method*s may be moving,
  // so we either have to flush all bcp data or convert it into bci.
  CodeCache::gc_prologue();
  Threads::gc_prologue();

  // Increment the invocation count
  _total_invocations++;

  // Capture heap size before collection for printing.
  size_t gch_prev_used = gch->used();

  // Capture used regions for each generation that will be
  // subject to collection, so that card table adjustments can
  // be made intelligently (see clear / invalidate further below).
  gch->save_used_regions(level);

  allocate_stacks();

  mark_sweep_phase1(level, clear_all_softrefs);

  mark_sweep_phase2();

  // Don't add any more derived pointers during phase3
  COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
  COMPILER2_PRESENT(DerivedPointerTable::set_active(false));

  mark_sweep_phase3(level);

  mark_sweep_phase4();

  restore_marks();

  // Set saved marks for allocation profiler (and other things? -- dld)
  // (Should this be in general part?)
  gch->save_marks();

  deallocate_stacks();

  // If compaction completely evacuated all generations younger than this
  // one, then we can clear the card table.  Otherwise, we must invalidate
  // it (consider all cards dirty).  In the future, we might consider doing
  // compaction within generations only, and doing card-table sliding.
  bool all_empty = true;
  for (int i = 0; all_empty && i < level; i++) {
    Generation* g = gch->get_gen(i);
    all_empty = all_empty && gch->get_gen(i)->used() == 0;
  }
  GenRemSet* rs = gch->rem_set();
  Generation* old_gen = gch->get_gen(level);
  // Clear/invalidate below make use of the "prev_used_regions" saved earlier.
  if (all_empty) {
    // We've evacuated all generations below us.
    rs->clear_into_younger(old_gen);
  } else {
    // Invalidate the cards corresponding to the currently used
    // region and clear those corresponding to the evacuated region.
    rs->invalidate_or_clear(old_gen);
  }

  Threads::gc_epilogue();
  CodeCache::gc_epilogue();
  JvmtiExport::gc_epilogue();

  if (PrintGC && !PrintGCDetails) {
    gch->print_heap_change(gch_prev_used);
  }

  // refs processing: clean slate
  _ref_processor = NULL;

  // Update heap occupancy information which is used as
  // input to soft ref clearing policy at the next gc.
  Universe::update_heap_info_at_gc();

  // Update time of last gc for all generations we collected
  // (which curently is all the generations in the heap).
  // We need to use a monotonically non-deccreasing time in ms
  // or we will see time-warp warnings and os::javaTimeMillis()
  // does not guarantee monotonicity.
//.........这里部分代码省略.........