view src/share/vm/gc_implementation/g1/satbQueue.hpp @ 2034:7e37af9d69ef

7011379: G1: overly long concurrent marking cycles Summary: This changeset introduces filtering of SATB buffers at the point when they are about to be enqueued. If this filtering clears enough entries on each buffer, the buffer can then be re-used and not enqueued. This cuts down the number of SATB buffers that need to be processed by the concurrent marking threads. Reviewed-by: johnc, ysr
author tonyp
date Wed, 19 Jan 2011 09:35:17 -0500
parents f95d63e2154a
children 2ace1c4ee8da
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 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
 * 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
 * or visit if you need additional information or have any
 * questions.


#include "gc_implementation/g1/ptrQueue.hpp"

class ObjectClosure;
class JavaThread;

// A ptrQueue whose elements are "oops", pointers to object heads.
class ObjPtrQueue: public PtrQueue {
  ObjPtrQueue(PtrQueueSet* qset, bool perm = false) :
    // SATB queues are only active during marking cycles. We create
    // them with their active field set to false. If a thread is
    // created during a cycle and its SATB queue needs to be activated
    // before the thread starts running, we'll need to set its active
    // field to true. This is done in JavaThread::initialize_queues().
    PtrQueue(qset, perm, false /* active */) { }

  // Overrides PtrQueue::should_enqueue_buffer(). See the method's
  // definition for more information.
  virtual bool should_enqueue_buffer();

  // Apply the closure to all elements, and reset the index to make the
  // buffer empty.
  void apply_closure(ObjectClosure* cl);

  // Apply the closure to all elements of "buf", down to "index" (inclusive.)
  static void apply_closure_to_buffer(ObjectClosure* cl,
                                      void** buf, size_t index, size_t sz);

  void verify_oops_in_buffer() NOT_DEBUG_RETURN;

class SATBMarkQueueSet: public PtrQueueSet {
  ObjectClosure* _closure;
  ObjectClosure** _par_closures;  // One per ParGCThread.

  ObjPtrQueue _shared_satb_queue;

  // Utility function to support sequential and parallel versions.  If
  // "par" is true, then "worker" is the par thread id; if "false", worker
  // is ignored.
  bool apply_closure_to_completed_buffer_work(bool par, int worker);

#ifdef ASSERT
  void dump_active_values(JavaThread* first, bool expected_active);
#endif // ASSERT


  void initialize(Monitor* cbl_mon, Mutex* fl_lock,
                  int process_completed_threshold,
                  Mutex* lock);

  static void handle_zero_index_for_thread(JavaThread* t);

  // Apply "set_active(b)" to all Java threads' SATB queues. It should be
  // called only with the world stopped. The method will assert that the
  // SATB queues of all threads it visits, as well as the SATB queue
  // set itself, has an active value same as expected_active.
  void set_active_all_threads(bool b, bool expected_active);

  // Register "blk" as "the closure" for all queues.  Only one such closure
  // is allowed.  The "apply_closure_to_completed_buffer" method will apply
  // this closure to a completed buffer, and "iterate_closure_all_threads"
  // applies it to partially-filled buffers (the latter should only be done
  // with the world stopped).
  void set_closure(ObjectClosure* closure);
  // Set the parallel closures: pointer is an array of pointers to
  // closures, one for each parallel GC thread.
  void set_par_closure(int i, ObjectClosure* closure);

  // If there is a registered closure for buffers, apply it to all entries
  // in all currently-active buffers.  This should only be applied at a
  // safepoint.  (Currently must not be called in parallel; this should
  // change in the future.)
  void iterate_closure_all_threads();
  // Parallel version of the above.
  void par_iterate_closure_all_threads(int worker);

  // If there exists some completed buffer, pop it, then apply the
  // registered closure to all its elements, and return true.  If no
  // completed buffers exist, return false.
  bool apply_closure_to_completed_buffer() {
    return apply_closure_to_completed_buffer_work(false, 0);
  // Parallel version of the above.
  bool par_apply_closure_to_completed_buffer(int worker) {
    return apply_closure_to_completed_buffer_work(true, worker);

  ObjPtrQueue* shared_satb_queue() { return &_shared_satb_queue; }

  // If a marking is being abandoned, reset any unprocessed log buffers.
  void abandon_partial_marking();