view hotspot/src/share/vm/gc_implementation/g1/g1RemSet.hpp @ 26701:f8ff74a6c058

8052172: Evacuation failure handling in G1 does not evacuate all objects if -XX:-G1DeferredRSUpdate is set Summary: Remove -XX:-G1DeferredRSUpdate functionality as it is racy. During evacuation failure handling, threads where evacuation failure handling occurred may try to add remembered sets to regions which remembered sets are currently being scanned. The iterator to handle the remembered set scan does not support addition of entries during scan and so may skip valid references. Reviewed-by: iveresov, brutisso, mgerdin
author tschatzl
date Tue, 16 Sep 2014 10:28:15 +0200
parents 4ee5901e205e
children 515ff48cf5f0
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 * 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
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 * questions.


#include "gc_implementation/g1/g1RemSetSummary.hpp"

// A G1RemSet provides ways of iterating over pointers into a selected
// collection set.

class G1CollectedHeap;
class CardTableModRefBarrierSet;
class ConcurrentG1Refine;

// A G1RemSet in which each heap region has a rem set that records the
// external heap references into it.  Uses a mod ref bs to track updates,
// so that they can be used to update the individual region remsets.

class G1RemSet: public CHeapObj<mtGC> {
  G1RemSetSummary _prev_period_summary;
  G1CollectedHeap* _g1;
  size_t _conc_refine_cards;
  uint n_workers();

  enum SomePrivateConstants {
    UpdateRStoMergeSync  = 0,
    MergeRStoDoDirtySync = 1,
    DoDirtySync          = 2,
    LastSync             = 3,

    SeqTask              = 0,
    NumSeqTasks          = 1

  CardTableModRefBS*     _ct_bs;
  SubTasksDone*          _seq_task;
  G1CollectorPolicy*     _g1p;

  ConcurrentG1Refine*    _cg1r;

  size_t*                _cards_scanned;
  size_t                 _total_cards_scanned;

  // Used for caching the closure that is responsible for scanning
  // references into the collection set.
  OopsInHeapRegionClosure** _cset_rs_update_cl;

  // Print the given summary info
  virtual void print_summary_info(G1RemSetSummary * summary, const char * header = NULL);
  // This is called to reset dual hash tables after the gc pause
  // is finished and the initial hash table is no longer being
  // scanned.
  void cleanupHRRS();

  G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);

  // Invoke "blk->do_oop" on all pointers into the collection set
  // from objects in regions outside the collection set (having
  // invoked "blk->set_region" to set the "from" region correctly
  // beforehand.)
  // Invoke code_root_cl->do_code_blob on the unmarked nmethods
  // on the strong code roots list for each region in the
  // collection set.
  // The "worker_i" param is for the parallel case where the id
  // of the worker thread calling this function can be helpful in
  // partitioning the work to be done. It should be the same as
  // the "i" passed to the calling thread's work(i) function.
  // In the sequential case this param will be ignored.
  void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
                                   CodeBlobClosure* code_root_cl,
                                   uint worker_i);

  // Prepare for and cleanup after an oops_into_collection_set_do
  // call.  Must call each of these once before and after (in sequential
  // code) any threads call oops_into_collection_set_do.  (This offers an
  // opportunity to sequential setup and teardown of structures needed by a
  // parallel iteration over the CS's RS.)
  void prepare_for_oops_into_collection_set_do();
  void cleanup_after_oops_into_collection_set_do();

  void scanRS(OopsInHeapRegionClosure* oc,
              CodeBlobClosure* code_root_cl,
              uint worker_i);

  void updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i);

  CardTableModRefBS* ct_bs() { return _ct_bs; }
  size_t cardsScanned() { return _total_cards_scanned; }

  // Record, if necessary, the fact that *p (where "p" is in region "from",
  // which is required to be non-NULL) has changed to a new non-NULL value.
  template <class T> void write_ref(HeapRegion* from, T* p);
  template <class T> void par_write_ref(HeapRegion* from, T* p, int tid);

  // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
  // or card, respectively, such that a region or card with a corresponding
  // 0 bit contains no part of any live object.  Eliminates any remembered
  // set entries that correspond to dead heap ranges.
  void scrub(BitMap* region_bm, BitMap* card_bm);

  // Like the above, but assumes is called in parallel: "worker_num" is the
  // parallel thread id of the current thread, and "claim_val" is the
  // value that should be used to claim heap regions.
  void scrub_par(BitMap* region_bm, BitMap* card_bm,
                 uint worker_num, int claim_val);

  // Refine the card corresponding to "card_ptr".
  // If check_for_refs_into_cset is true, a true result is returned
  // if the given card contains oops that have references into the
  // current collection set.
  virtual bool refine_card(jbyte* card_ptr,
                           uint worker_i,
                           bool check_for_refs_into_cset);

  // Print accumulated summary info from the start of the VM.
  virtual void print_summary_info();

  // Print accumulated summary info from the last time called.
  virtual void print_periodic_summary_info(const char* header);

  // Prepare remembered set for verification.
  virtual void prepare_for_verify();

  size_t conc_refine_cards() const {
    return _conc_refine_cards;

class CountNonCleanMemRegionClosure: public MemRegionClosure {
  G1CollectedHeap* _g1;
  int _n;
  HeapWord* _start_first;
  CountNonCleanMemRegionClosure(G1CollectedHeap* g1) :
    _g1(g1), _n(0), _start_first(NULL)
  void do_MemRegion(MemRegion mr);
  int n() { return _n; };
  HeapWord* start_first() { return _start_first; }

class UpdateRSOopClosure: public ExtendedOopClosure {
  HeapRegion* _from;
  G1RemSet* _rs;
  uint _worker_i;

  template <class T> void do_oop_work(T* p);

  UpdateRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
    _from(NULL), _rs(rs), _worker_i(worker_i)

  void set_from(HeapRegion* from) {
    assert(from != NULL, "from region must be non-NULL");
    _from = from;

  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
  virtual void do_oop(oop* p)       { do_oop_work(p); }

  // Override: this closure is idempotent.
  //  bool idempotent() { return true; }
  bool apply_to_weak_ref_discovered_field() { return true; }