psCompactionManager.cpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * 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 "incls/_precompiled.incl"
#include "incls/_psCompactionManager.cpp.incl"

PSOldGen*            ParCompactionManager::_old_gen = NULL;
ParCompactionManager**  ParCompactionManager::_manager_array = NULL;
OopTaskQueueSet*     ParCompactionManager::_stack_array = NULL;
ParCompactionManager::ObjArrayTaskQueueSet*
  ParCompactionManager::_objarray_queues = NULL;
ObjectStartArray*    ParCompactionManager::_start_array = NULL;
ParMarkBitMap*       ParCompactionManager::_mark_bitmap = NULL;
RegionTaskQueueSet*   ParCompactionManager::_region_array = NULL;

ParCompactionManager::ParCompactionManager() :
    _action(CopyAndUpdate) {

  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

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


  marking_stack()->initialize();

  // We want the overflow stack to be permanent
  _overflow_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(10, true);

  _objarray_queue.initialize();
  _objarray_overflow_stack =
    new (ResourceObj::C_HEAP) ObjArrayOverflowStack(10, true);

#ifdef USE_RegionTaskQueueWithOverflow
  region_stack()->initialize();
#else
  region_stack()->initialize();

  // We want the overflow stack to be permanent
  _region_overflow_stack =
    new (ResourceObj::C_HEAP) GrowableArray<size_t>(10, true);
#endif

  // Note that _revisit_klass_stack is allocated out of the
  // C heap (as opposed to out of ResourceArena).
  int size =
    (SystemDictionary::number_of_classes() * 2) * 2 / ParallelGCThreads;
  _revisit_klass_stack = new (ResourceObj::C_HEAP) GrowableArray<Klass*>(size, true);
  // From some experiments (#klass/k)^2 for k = 10 seems a better fit, but this will
  // have to do for now until we are able to investigate a more optimal setting.
  _revisit_mdo_stack = new (ResourceObj::C_HEAP) GrowableArray<DataLayout*>(size*2, true);

}

ParCompactionManager::~ParCompactionManager() {
  delete _overflow_stack;
  delete _objarray_overflow_stack;
  delete _revisit_klass_stack;
  delete _revisit_mdo_stack;
  // _manager_array and _stack_array are statics
  // shared with all instances of ParCompactionManager
  // should not be deallocated.
}

void ParCompactionManager::initialize(ParMarkBitMap* mbm) {
  assert(PSParallelCompact::gc_task_manager() != NULL,
    "Needed for initialization");

  _mark_bitmap = mbm;

  uint parallel_gc_threads = PSParallelCompact::gc_task_manager()->workers();

  assert(_manager_array == NULL, "Attempt to initialize twice");
  _manager_array = NEW_C_HEAP_ARRAY(ParCompactionManager*, parallel_gc_threads+1 );
  guarantee(_manager_array != NULL, "Could not allocate manager_array");

  _stack_array = new OopTaskQueueSet(parallel_gc_threads);
  guarantee(_stack_array != NULL, "Could not allocate stack_array");
  _objarray_queues = new ObjArrayTaskQueueSet(parallel_gc_threads);
  guarantee(_objarray_queues != NULL, "Could not allocate objarray_queues");
  _region_array = new RegionTaskQueueSet(parallel_gc_threads);
  guarantee(_region_array != NULL, "Could not allocate region_array");

  // Create and register the ParCompactionManager(s) for the worker threads.
  for(uint i=0; i<parallel_gc_threads; i++) {
    _manager_array[i] = new ParCompactionManager();
    guarantee(_manager_array[i] != NULL, "Could not create ParCompactionManager");
    stack_array()->register_queue(i, _manager_array[i]->marking_stack());
    _objarray_queues->register_queue(i, &_manager_array[i]->_objarray_queue);
#ifdef USE_RegionTaskQueueWithOverflow
    region_array()->register_queue(i, _manager_array[i]->region_stack()->task_queue());
#else
    region_array()->register_queue(i, _manager_array[i]->region_stack());
#endif
  }

  // The VMThread gets its own ParCompactionManager, which is not available
  // for work stealing.
  _manager_array[parallel_gc_threads] = new ParCompactionManager();
  guarantee(_manager_array[parallel_gc_threads] != NULL,
    "Could not create ParCompactionManager");
  assert(PSParallelCompact::gc_task_manager()->workers() != 0,
    "Not initialized?");
}

bool ParCompactionManager::should_update() {
  assert(action() != NotValid, "Action is not set");
  return (action() == ParCompactionManager::Update) ||
         (action() == ParCompactionManager::CopyAndUpdate) ||
         (action() == ParCompactionManager::UpdateAndCopy);
}

bool ParCompactionManager::should_copy() {
  assert(action() != NotValid, "Action is not set");
  return (action() == ParCompactionManager::Copy) ||
         (action() == ParCompactionManager::CopyAndUpdate) ||
         (action() == ParCompactionManager::UpdateAndCopy);
}

bool ParCompactionManager::should_verify_only() {
  assert(action() != NotValid, "Action is not set");
  return action() == ParCompactionManager::VerifyUpdate;
}

bool ParCompactionManager::should_reset_only() {
  assert(action() != NotValid, "Action is not set");
  return action() == ParCompactionManager::ResetObjects;
}

// For now save on a stack
void ParCompactionManager::save_for_scanning(oop m) {
  stack_push(m);
}

void ParCompactionManager::stack_push(oop obj) {

  if(!marking_stack()->push(obj)) {
    overflow_stack()->push(obj);
  }
}

oop ParCompactionManager::retrieve_for_scanning() {

  // Should not be used in the parallel case
  ShouldNotReachHere();
  return NULL;
}

// Save region on a stack
void ParCompactionManager::save_for_processing(size_t region_index) {
#ifdef ASSERT
  const ParallelCompactData& sd = PSParallelCompact::summary_data();
  ParallelCompactData::RegionData* const region_ptr = sd.region(region_index);
  assert(region_ptr->claimed(), "must be claimed");
  assert(region_ptr->_pushed++ == 0, "should only be pushed once");
#endif
  region_stack_push(region_index);
}

void ParCompactionManager::region_stack_push(size_t region_index) {

#ifdef USE_RegionTaskQueueWithOverflow
  region_stack()->save(region_index);
#else
  if(!region_stack()->push(region_index)) {
    region_overflow_stack()->push(region_index);
  }
#endif
}

bool ParCompactionManager::retrieve_for_processing(size_t& region_index) {
#ifdef USE_RegionTaskQueueWithOverflow
  return region_stack()->retrieve(region_index);
#else
  // Should not be used in the parallel case
  ShouldNotReachHere();
  return false;
#endif
}

ParCompactionManager*
ParCompactionManager::gc_thread_compaction_manager(int index) {
  assert(index >= 0 && index < (int)ParallelGCThreads, "index out of range");
  assert(_manager_array != NULL, "Sanity");
  return _manager_array[index];
}

void ParCompactionManager::reset() {
  for(uint i=0; i<ParallelGCThreads+1; i++) {
    manager_array(i)->revisit_klass_stack()->clear();
    manager_array(i)->revisit_mdo_stack()->clear();
  }
}

void ParCompactionManager::follow_marking_stacks() {
  do {
    // Drain the overflow stack first, to allow stealing from the marking stack.
    oop obj;
    while (!overflow_stack()->is_empty()) {
      overflow_stack()->pop()->follow_contents(this);
    }
    while (marking_stack()->pop_local(obj)) {
      obj->follow_contents(this);
    }

    // Process ObjArrays one at a time to avoid marking stack bloat.
    ObjArrayTask task;
    if (!_objarray_overflow_stack->is_empty()) {
      task = _objarray_overflow_stack->pop();
      objArrayKlass* const k = (objArrayKlass*)task.obj()->blueprint();
      k->oop_follow_contents(this, task.obj(), task.index());
    } else if (_objarray_queue.pop_local(task)) {
      objArrayKlass* const k = (objArrayKlass*)task.obj()->blueprint();
      k->oop_follow_contents(this, task.obj(), task.index());
    }
  } while (!marking_stacks_empty());

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

void ParCompactionManager::drain_region_overflow_stack() {
  size_t region_index = (size_t) -1;
  while(region_stack()->retrieve_from_overflow(region_index)) {
    PSParallelCompact::fill_and_update_region(this, region_index);
  }
}

void ParCompactionManager::drain_region_stacks() {
#ifdef ASSERT
  ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
  assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
  MutableSpace* to_space = heap->young_gen()->to_space();
  MutableSpace* old_space = heap->old_gen()->object_space();
  MutableSpace* perm_space = heap->perm_gen()->object_space();
#endif /* ASSERT */

#if 1 // def DO_PARALLEL - the serial code hasn't been updated
  do {

#ifdef USE_RegionTaskQueueWithOverflow
    // Drain overflow stack first, so other threads can steal from
    // claimed stack while we work.
    size_t region_index = (size_t) -1;
    while(region_stack()->retrieve_from_overflow(region_index)) {
      PSParallelCompact::fill_and_update_region(this, region_index);
    }

    while (region_stack()->retrieve_from_stealable_queue(region_index)) {
      PSParallelCompact::fill_and_update_region(this, region_index);
    }
  } while (!region_stack()->is_empty());
#else
    // Drain overflow stack first, so other threads can steal from
    // claimed stack while we work.
    while(!region_overflow_stack()->is_empty()) {
      size_t region_index = region_overflow_stack()->pop();
      PSParallelCompact::fill_and_update_region(this, region_index);
    }

    size_t region_index = -1;
    // obj is a reference!!!
    while (region_stack()->pop_local(region_index)) {
      // It would be nice to assert about the type of objects we might
      // pop, but they can come from anywhere, unfortunately.
      PSParallelCompact::fill_and_update_region(this, region_index);
    }
  } while((region_stack()->size() != 0) ||
          (region_overflow_stack()->length() != 0));
#endif

#ifdef USE_RegionTaskQueueWithOverflow
  assert(region_stack()->is_empty(), "Sanity");
#else
  assert(region_stack()->size() == 0, "Sanity");
  assert(region_overflow_stack()->length() == 0, "Sanity");
#endif
#else
  oop obj;
  while (obj = retrieve_for_scanning()) {
    obj->follow_contents(this);
  }
#endif
}

#ifdef ASSERT
bool ParCompactionManager::stacks_have_been_allocated() {
  return (revisit_klass_stack()->data_addr() != NULL &&
          revisit_mdo_stack()->data_addr() != NULL);
}
#endif