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

/*
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 * 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.
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#include "precompiled.hpp"
#include "gc/parallel/objectStartArray.hpp"
#include "gc/parallel/parMarkBitMap.inline.hpp"
#include "gc/parallel/parallelScavengeHeap.hpp"
#include "gc/parallel/psCompactionManager.inline.hpp"
#include "gc/parallel/psOldGen.hpp"
#include "gc/parallel/psParallelCompact.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::OopTaskQueueSet*      ParCompactionManager::_oop_task_queues = nullptr;
ParCompactionManager::ObjArrayTaskQueueSet* ParCompactionManager::_objarray_task_queues = nullptr;
ParCompactionManager::RegionTaskQueueSet*   ParCompactionManager::_region_task_queues = 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;

ParCompactionManager::ParCompactionManager() {

  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();

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

  reset_bitmap_query_cache();

  _deferred_obj_array = new (mtGC) GrowableArray<HeapWord*>(10, mtGC);
}

void ParCompactionManager::initialize(ParMarkBitMap* mbm) {
  assert(ParallelScavengeHeap::heap() != nullptr,
    "Needed for initialization");

  _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);

  _oop_task_queues = new OopTaskQueueSet(parallel_gc_threads);
  _objarray_task_queues = new ObjArrayTaskQueueSet(parallel_gc_threads);
  _region_task_queues = new RegionTaskQueueSet(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();
    oop_task_queues()->register_queue(i, _manager_array[i]->oop_stack());
    _objarray_task_queues->register_queue(i, &_manager_array[i]->_objarray_stack);
    region_task_queues()->register_queue(i, _manager_array[i]->region_stack());
  }

  assert(ParallelScavengeHeap::heap()->workers().max_workers() != 0,
    "Not initialized?");

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

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

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

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];
}

inline void ParCompactionManager::publish_and_drain_oop_tasks() {
  oop obj;
  while (oop_stack()->pop_overflow(obj)) {
    if (!oop_stack()->try_push_to_taskqueue(obj)) {
      follow_contents(obj);
    }
  }
  while (oop_stack()->pop_local(obj)) {
    follow_contents(obj);
  }
}

bool ParCompactionManager::publish_or_pop_objarray_tasks(ObjArrayTask& task) {
  while (_objarray_stack.pop_overflow(task)) {
    if (!_objarray_stack.try_push_to_taskqueue(task)) {
      return true;
    }
  }
  return false;
}

void ParCompactionManager::follow_marking_stacks() {
  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.
    publish_and_drain_oop_tasks();

    // Process ObjArrays one at a time to avoid marking stack bloat.
    ObjArrayTask task;
    if (publish_or_pop_objarray_tasks(task) ||
        _objarray_stack.pop_local(task)) {
      follow_array((objArrayOop)task.obj(), task.index());
    }
  } while (!marking_stacks_empty());

  assert(marking_stacks_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());
}

void ParCompactionManager::drain_deferred_objects() {
  while (!_deferred_obj_array->is_empty()) {
    HeapWord* addr = _deferred_obj_array->pop();
    assert(addr != nullptr, "expected a deferred object");
    PSParallelCompact::update_deferred_object(this, addr);
  }
  _deferred_obj_array->clear_and_deallocate();
}

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();
}

void ParCompactionManager::push_deferred_object(HeapWord* addr) {
  _deferred_obj_array->push(addr);
}

#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_stacks_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