jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@0bfd3fb24150 (annotated)

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@0bfd3fb24150 (annotated)

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp

Tue, 13 Apr 2010 13:52:10 -0700

author: jmasa
date: Tue, 13 Apr 2010 13:52:10 -0700
changeset 1822: 0bfd3fb24150
parent 1696: 0414c1049f15
child 1825: f9ec1e4bbb44
permissions: -rw-r--r--

6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
Summary: Ensure a full GC that clears SoftReferences before throwing an out-of-memory
Reviewed-by: ysr, jcoomes

 /*
  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.
  * 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.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 // Remembered set for a heap region.  Represent a set of "cards" that
 // contain pointers into the owner heap region.  Cards are defined somewhat
 // abstractly, in terms of what the "BlockOffsetTable" in use can parse.
 class G1CollectedHeap;
 class G1BlockOffsetSharedArray;
 class HeapRegion;
 class HeapRegionRemSetIterator;
 class PosParPRT;
 class SparsePRT;
 // The "_coarse_map" is a bitmap with one bit for each region, where set
 // bits indicate that the corresponding region may contain some pointer
 // into the owning region.
 // The "_fine_grain_entries" array is an open hash table of PerRegionTables
 // (PRTs), indicating regions for which we're keeping the RS as a set of
 // cards.  The strategy is to cap the size of the fine-grain table,
 // deleting an entry and setting the corresponding coarse-grained bit when
 // we would overflow this cap.
 // We use a mixture of locking and lock-free techniques here.  We allow
 // threads to locate PRTs without locking, but threads attempting to alter
 // a bucket list obtain a lock.  This means that any failing attempt to
 // find a PRT must be retried with the lock.  It might seem dangerous that
 // a read can find a PRT that is concurrently deleted.  This is all right,
 // because:
 //
 //   1) We only actually free PRT's at safe points (though we reuse them at
 //      other times).
 //   2) We find PRT's in an attempt to add entries.  If a PRT is deleted,
 //      it's _coarse_map bit is set, so the that we were attempting to add
 //      is represented.  If a deleted PRT is re-used, a thread adding a bit,
 //      thinking the PRT is for a different region, does no harm.
 class OtherRegionsTable VALUE_OBJ_CLASS_SPEC {
   friend class HeapRegionRemSetIterator;
   G1CollectedHeap* _g1h;
   Mutex            _m;
   HeapRegion*      _hr;
   // These are protected by "_m".
   BitMap      _coarse_map;
   size_t      _n_coarse_entries;
   static jint _n_coarsenings;
   PosParPRT** _fine_grain_regions;
   size_t      _n_fine_entries;
 #define SAMPLE_FOR_EVICTION 1
 #if SAMPLE_FOR_EVICTION
   size_t        _fine_eviction_start;
   static size_t _fine_eviction_stride;
   static size_t _fine_eviction_sample_size;
 #endif
   SparsePRT   _sparse_table;
   // These are static after init.
   static size_t _max_fine_entries;
   static size_t _mod_max_fine_entries_mask;
   // Requires "prt" to be the first element of the bucket list appropriate
   // for "hr".  If this list contains an entry for "hr", return it,
   // otherwise return "NULL".
   PosParPRT* find_region_table(size_t ind, HeapRegion* hr) const;
   // Find, delete, and return a candidate PosParPRT, if any exists,
   // adding the deleted region to the coarse bitmap.  Requires the caller
   // to hold _m, and the fine-grain table to be full.
   PosParPRT* delete_region_table();
   // If a PRT for "hr" is in the bucket list indicated by "ind" (which must
   // be the correct index for "hr"), delete it and return true; else return
   // false.
   bool del_single_region_table(size_t ind, HeapRegion* hr);
   static jint _cache_probes;
   static jint _cache_hits;
   // Indexed by thread X heap region, to minimize thread contention.
   static int** _from_card_cache;
   static size_t _from_card_cache_max_regions;
   static size_t _from_card_cache_mem_size;
 public:
   OtherRegionsTable(HeapRegion* hr);
   HeapRegion* hr() const { return _hr; }
   // For now.  Could "expand" some tables in the future, so that this made
   // sense.
   void add_reference(OopOrNarrowOopStar from, int tid);
   void add_reference(OopOrNarrowOopStar from) {
     return add_reference(from, 0);
   }
   // Removes any entries shown by the given bitmaps to contain only dead
   // objects.
   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
   // Not const because it takes a lock.
   size_t occupied() const;
   size_t occ_fine() const;
   size_t occ_coarse() const;
   size_t occ_sparse() const;
   static jint n_coarsenings() { return _n_coarsenings; }
   // Returns size in bytes.
   // Not const because it takes a lock.
   size_t mem_size() const;
   static size_t static_mem_size();
   static size_t fl_mem_size();
   bool contains_reference(OopOrNarrowOopStar from) const;
   bool contains_reference_locked(OopOrNarrowOopStar from) const;
   void clear();
   // Specifically clear the from_card_cache.
   void clear_fcc();
   // "from_hr" is being cleared; remove any entries from it.
   void clear_incoming_entry(HeapRegion* from_hr);
   // Declare the heap size (in # of regions) to the OtherRegionsTable.
   // (Uses it to initialize from_card_cache).
   static void init_from_card_cache(size_t max_regions);
   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
   // Make sure any entries for higher regions are invalid.
   static void shrink_from_card_cache(size_t new_n_regs);
   static void print_from_card_cache();
 };
 class HeapRegionRemSet : public CHeapObj {
   friend class VMStructs;
   friend class HeapRegionRemSetIterator;
 public:
   enum Event {
     Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd
   };
 private:
   G1BlockOffsetSharedArray* _bosa;
   G1BlockOffsetSharedArray* bosa() const { return _bosa; }
   OtherRegionsTable _other_regions;
   // One set bit for every region that has an entry for this one.
   BitMap _outgoing_region_map;
   // Clear entries for the current region in any rem sets named in
   // the _outgoing_region_map.
   void clear_outgoing_entries();
   enum ParIterState { Unclaimed, Claimed, Complete };
   volatile ParIterState _iter_state;
   volatile jlong _iter_claimed;
   // Unused unless G1RecordHRRSOops is true.
   static const int MaxRecorded = 1000000;
   static OopOrNarrowOopStar* _recorded_oops;
   static HeapWord**          _recorded_cards;
   static HeapRegion**        _recorded_regions;
   static int                 _n_recorded;
   static const int MaxRecordedEvents = 1000;
   static Event*       _recorded_events;
   static int*         _recorded_event_index;
   static int          _n_recorded_events;
   static void print_event(outputStream* str, Event evnt);
 public:
   HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
                    HeapRegion* hr);
   static int num_par_rem_sets();
   static void setup_remset_size();
   HeapRegion* hr() const {
     return _other_regions.hr();
   }
   size_t occupied() const {
     return _other_regions.occupied();
   }
   size_t occ_fine() const {
     return _other_regions.occ_fine();
   }
   size_t occ_coarse() const {
     return _other_regions.occ_coarse();
   }
   size_t occ_sparse() const {
     return _other_regions.occ_sparse();
   }
   static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); }
   /* Used in the sequential case.  Returns "true" iff this addition causes
      the size limit to be reached. */
   void add_reference(OopOrNarrowOopStar from) {
     _other_regions.add_reference(from);
   }
   /* Used in the parallel case.  Returns "true" iff this addition causes
      the size limit to be reached. */
   void add_reference(OopOrNarrowOopStar from, int tid) {
     _other_regions.add_reference(from, tid);
   }
   // Records the fact that the current region contains an outgoing
   // reference into "to_hr".
   void add_outgoing_reference(HeapRegion* to_hr);
   // Removes any entries shown by the given bitmaps to contain only dead
   // objects.
   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
   // The region is being reclaimed; clear its remset, and any mention of
   // entries for this region in other remsets.
   void clear();
   // Forget any entries due to pointers from "from_hr".
   void clear_incoming_entry(HeapRegion* from_hr) {
     _other_regions.clear_incoming_entry(from_hr);
   }
 #if 0
   virtual void cleanup() = 0;
 #endif
   // Should be called from single-threaded code.
   void init_for_par_iteration();
   // Attempt to claim the region.  Returns true iff this call caused an
   // atomic transition from Unclaimed to Claimed.
   bool claim_iter();
   // Sets the iteration state to "complete".
   void set_iter_complete();
   // Returns "true" iff the region's iteration is complete.
   bool iter_is_complete();
   // Support for claiming blocks of cards during iteration
   void set_iter_claimed(size_t x) { _iter_claimed = (jlong)x; }
   size_t iter_claimed() const { return (size_t)_iter_claimed; }
   // Claim the next block of cards
   size_t iter_claimed_next(size_t step) {
     size_t current, next;
     do {
       current = iter_claimed();
       next = current + step;
     } while (Atomic::cmpxchg((jlong)next, &_iter_claimed, (jlong)current) != (jlong)current);
     return current;
   }
   // Initialize the given iterator to iterate over this rem set.
   void init_iterator(HeapRegionRemSetIterator* iter) const;
 #if 0
   // Apply the "do_card" method to the start address of every card in the
   // rem set.  Returns false if some application of the closure aborted.
   virtual bool card_iterate(CardClosure* iter) = 0;
 #endif
   // The actual # of bytes this hr_remset takes up.
   size_t mem_size() {
     return _other_regions.mem_size()
       // This correction is necessary because the above includes the second
       // part.
       + sizeof(this) - sizeof(OtherRegionsTable);
   }
   // Returns the memory occupancy of all static data structures associated
   // with remembered sets.
   static size_t static_mem_size() {
     return OtherRegionsTable::static_mem_size();
   }
   // Returns the memory occupancy of all free_list data structures associated
   // with remembered sets.
   static size_t fl_mem_size() {
     return OtherRegionsTable::fl_mem_size();
   }
   bool contains_reference(OopOrNarrowOopStar from) const {
     return _other_regions.contains_reference(from);
   }
   void print() const;
   // Called during a stop-world phase to perform any deferred cleanups.
   // The second version may be called by parallel threads after then finish
   // collection work.
   static void cleanup();
   static void par_cleanup();
   // Declare the heap size (in # of regions) to the HeapRegionRemSet(s).
   // (Uses it to initialize from_card_cache).
   static void init_heap(size_t max_regions) {
     OtherRegionsTable::init_from_card_cache(max_regions);
   }
   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
   static void shrink_heap(size_t new_n_regs) {
     OtherRegionsTable::shrink_from_card_cache(new_n_regs);
   }
 #ifndef PRODUCT
   static void print_from_card_cache() {
     OtherRegionsTable::print_from_card_cache();
   }
 #endif
   static void record(HeapRegion* hr, OopOrNarrowOopStar f);
   static void print_recorded();
   static void record_event(Event evnt);
   // Run unit tests.
 #ifndef PRODUCT
   static void test();
 #endif
 };
 class HeapRegionRemSetIterator : public CHeapObj {
   // The region over which we're iterating.
   const HeapRegionRemSet* _hrrs;
   // Local caching of HRRS fields.
   const BitMap*             _coarse_map;
   PosParPRT**               _fine_grain_regions;
   G1BlockOffsetSharedArray* _bosa;
   G1CollectedHeap*          _g1h;
   // The number yielded since initialization.
   size_t _n_yielded_fine;
   size_t _n_yielded_coarse;
   size_t _n_yielded_sparse;
   // If true we're iterating over the coarse table; if false the fine
   // table.
   enum IterState {
     Sparse,
     Fine,
     Coarse
   };
   IterState _is;
   // In both kinds of iteration, heap offset of first card of current
   // region.
   size_t _cur_region_card_offset;
   // Card offset within cur region.
   size_t _cur_region_cur_card;
   // Coarse table iteration fields:
   // Current region index;
   int _coarse_cur_region_index;
   int _coarse_cur_region_cur_card;
   bool coarse_has_next(size_t& card_index);
   // Fine table iteration fields:
   // Index of bucket-list we're working on.
   int _fine_array_index;
   // Per Region Table we're doing within current bucket list.
   PosParPRT* _fine_cur_prt;
   /* SparsePRT::*/ SparsePRTIter _sparse_iter;
   void fine_find_next_non_null_prt();
   bool fine_has_next();
   bool fine_has_next(size_t& card_index);
 public:
   // We require an iterator to be initialized before use, so the
   // constructor does little.
   HeapRegionRemSetIterator();
   void initialize(const HeapRegionRemSet* hrrs);
   // If there remains one or more cards to be yielded, returns true and
   // sets "card_index" to one of those cards (which is then considered
   // yielded.)   Otherwise, returns false (and leaves "card_index"
   // undefined.)
   bool has_next(size_t& card_index);
   size_t n_yielded_fine() { return _n_yielded_fine; }
   size_t n_yielded_coarse() { return _n_yielded_coarse; }
   size_t n_yielded_sparse() { return _n_yielded_sparse; }
   size_t n_yielded() {
     return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse();
   }
 };
 #if 0
 class CardClosure: public Closure {
 public:
   virtual void do_card(HeapWord* card_start) = 0;
 };
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp@0bfd3fb24150 (annotated)

src/share/vm/gc_implementation/g1/heapRegionRemSet.hpp