src/hotspot/share/gc/parallel/psCompactionManager.cpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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#include "gc/parallel/objectStartArray.hpp"
#include "gc/parallel/parallelScavengeHeap.hpp"
#include "gc/parallel/parMarkBitMap.inline.hpp"
#include "gc/parallel/psCompactionManager.inline.hpp"
#include "gc/parallel/psOldGen.hpp"
#include "gc/parallel/psParallelCompact.inline.hpp"
#include "gc/shared/partialArraySplitter.inline.hpp"
#include "gc/shared/partialArrayState.hpp"
#include "gc/shared/preservedMarks.inline.hpp"
#include "gc/shared/taskqueue.inline.hpp"
#include "logging/log.hpp"
#include "memory/iterator.inline.hpp"
#include "oops/access.inline.hpp"
#include "oops/compressedOops.inline.hpp"
#include "oops/instanceKlass.inline.hpp"
#include "oops/instanceMirrorKlass.inline.hpp"
#include "oops/objArrayKlass.inline.hpp"
#include "oops/oop.inline.hpp"

PSOldGen*               ParCompactionManager::_old_gen = nullptr;
ParCompactionManager**  ParCompactionManager::_manager_array = nullptr;

ParCompactionManager::PSMarkTasksQueueSet*  ParCompactionManager::_marking_stacks = nullptr;
ParCompactionManager::RegionTaskQueueSet*   ParCompactionManager::_region_task_queues = nullptr;
PartialArrayStateManager* ParCompactionManager::_partial_array_state_manager = nullptr;

ObjectStartArray*    ParCompactionManager::_start_array = nullptr;
ParMarkBitMap*       ParCompactionManager::_mark_bitmap = nullptr;
GrowableArray<size_t >* ParCompactionManager::_shadow_region_array = nullptr;
Monitor*                ParCompactionManager::_shadow_region_monitor = nullptr;

PreservedMarksSet* ParCompactionManager::_preserved_marks_set = nullptr;

ParCompactionManager::ParCompactionManager(PreservedMarks* preserved_marks,
                                           ReferenceProcessor* ref_processor,
                                           uint parallel_gc_threads)
  :_partial_array_splitter(_partial_array_state_manager, parallel_gc_threads, ObjArrayMarkingStride),
   _mark_and_push_closure(this, ref_processor) {

  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();

  _old_gen = heap->old_gen();
  _start_array = old_gen()->start_array();

  _preserved_marks = preserved_marks;
  _marking_stats_cache = nullptr;
}

void ParCompactionManager::initialize(ParMarkBitMap* mbm) {
  assert(ParallelScavengeHeap::heap() != nullptr, "Needed for initialization");
  assert(PSParallelCompact::ref_processor() != nullptr, "precondition");
  assert(ParallelScavengeHeap::heap()->workers().max_workers() != 0, "Not initialized?");

  _mark_bitmap = mbm;

  uint parallel_gc_threads = ParallelScavengeHeap::heap()->workers().max_workers();

  assert(_manager_array == nullptr, "Attempt to initialize twice");
  _manager_array = NEW_C_HEAP_ARRAY(ParCompactionManager*, parallel_gc_threads, mtGC);

  assert(_partial_array_state_manager == nullptr, "Attempt to initialize twice");
  _partial_array_state_manager
    = new PartialArrayStateManager(parallel_gc_threads);
  _marking_stacks = new PSMarkTasksQueueSet(parallel_gc_threads);
  _region_task_queues = new RegionTaskQueueSet(parallel_gc_threads);

  _preserved_marks_set = new PreservedMarksSet(true);
  _preserved_marks_set->init(parallel_gc_threads);

  // Create and register the ParCompactionManager(s) for the worker threads.
  for(uint i=0; i<parallel_gc_threads; i++) {
    _manager_array[i] = new ParCompactionManager(_preserved_marks_set->get(i),
                                                 PSParallelCompact::ref_processor(),
                                                 parallel_gc_threads);
    marking_stacks()->register_queue(i, _manager_array[i]->marking_stack());
    region_task_queues()->register_queue(i, _manager_array[i]->region_stack());
  }

  _shadow_region_array = new (mtGC) GrowableArray<size_t >(10, mtGC);

  _shadow_region_monitor = new Monitor(Mutex::nosafepoint, "CompactionManager_lock");
}

void ParCompactionManager::flush_all_string_dedup_requests() {
  uint parallel_gc_threads = ParallelScavengeHeap::heap()->workers().max_workers();
  for (uint i=0; i<parallel_gc_threads; i++) {
    _manager_array[i]->flush_string_dedup_requests();
  }
}

ParCompactionManager*
ParCompactionManager::gc_thread_compaction_manager(uint index) {
  assert(index < ParallelGCThreads, "index out of range");
  assert(_manager_array != nullptr, "Sanity");
  return _manager_array[index];
}

void ParCompactionManager::push_objArray(oop obj) {
  assert(obj->is_objArray(), "precondition");
  _mark_and_push_closure.do_klass(obj->klass());

  objArrayOop obj_array = objArrayOop(obj);
  size_t array_length = obj_array->length();
  size_t initial_chunk_size =
    _partial_array_splitter.start(&_marking_stack, obj_array, nullptr, array_length);
  follow_array(obj_array, 0, initial_chunk_size);
}

void ParCompactionManager::process_array_chunk(PartialArrayState* state, bool stolen) {
  // Access before release by claim().
  oop obj = state->source();
  PartialArraySplitter::Claim claim =
    _partial_array_splitter.claim(state, &_marking_stack, stolen);
  follow_array(objArrayOop(obj), claim._start, claim._end);
}

void ParCompactionManager::follow_marking_stacks() {
  ScannerTask task;
  do {
    // First, try to move tasks from the overflow stack into the shared buffer, so
    // that other threads can steal. Otherwise process the overflow stack first.
    while (marking_stack()->pop_overflow(task)) {
      if (!marking_stack()->try_push_to_taskqueue(task)) {
        follow_contents(task, false);
      }
    }
    while (marking_stack()->pop_local(task)) {
      follow_contents(task, false);
    }
  } while (!marking_stack_empty());

  assert(marking_stack_empty(), "Sanity");
}

void ParCompactionManager::drain_region_stacks() {
  do {
    // Drain overflow stack first so other threads can steal.
    size_t region_index;
    while (region_stack()->pop_overflow(region_index)) {
      PSParallelCompact::fill_and_update_region(this, region_index);
    }

    while (region_stack()->pop_local(region_index)) {
      PSParallelCompact::fill_and_update_region(this, region_index);
    }
  } while (!region_stack()->is_empty());
}

size_t ParCompactionManager::pop_shadow_region_mt_safe(PSParallelCompact::RegionData* region_ptr) {
  MonitorLocker ml(_shadow_region_monitor, Mutex::_no_safepoint_check_flag);
  while (true) {
    if (!_shadow_region_array->is_empty()) {
      return _shadow_region_array->pop();
    }
    // Check if the corresponding heap region is available now.
    // If so, we don't need to get a shadow region anymore, and
    // we return InvalidShadow to indicate such a case.
    if (region_ptr->claimed()) {
      return InvalidShadow;
    }
    ml.wait(1);
  }
}

void ParCompactionManager::push_shadow_region_mt_safe(size_t shadow_region) {
  MonitorLocker ml(_shadow_region_monitor, Mutex::_no_safepoint_check_flag);
  _shadow_region_array->push(shadow_region);
  ml.notify();
}

void ParCompactionManager::push_shadow_region(size_t shadow_region) {
  _shadow_region_array->push(shadow_region);
}

void ParCompactionManager::remove_all_shadow_regions() {
  _shadow_region_array->clear();
}


#if TASKQUEUE_STATS
void ParCompactionManager::print_and_reset_taskqueue_stats() {
  marking_stacks()->print_and_reset_taskqueue_stats("Marking Stacks");

  auto get_pa_stats = [&](uint i) {
    return _manager_array[i]->partial_array_task_stats();
  };
  PartialArrayTaskStats::log_set(ParallelGCThreads, get_pa_stats,
                                 "Partial Array Task Stats");
  uint parallel_gc_threads = ParallelScavengeHeap::heap()->workers().max_workers();
  for (uint i = 0; i < parallel_gc_threads; ++i) {
    get_pa_stats(i)->reset();
  }
}

PartialArrayTaskStats* ParCompactionManager::partial_array_task_stats() {
  return _partial_array_splitter.stats();
}
#endif // TASKQUEUE_STATS

#ifdef ASSERT
void ParCompactionManager::verify_all_marking_stack_empty() {
  uint parallel_gc_threads = ParallelGCThreads;
  for (uint i = 0; i < parallel_gc_threads; i++) {
    assert(_manager_array[i]->marking_stack_empty(), "Marking stack should be empty");
  }
}

void ParCompactionManager::verify_all_region_stack_empty() {
  uint parallel_gc_threads = ParallelGCThreads;
  for (uint i = 0; i < parallel_gc_threads; i++) {
    assert(_manager_array[i]->region_stack()->is_empty(), "Region stack should be empty");
  }
}
#endif