jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp@0bfd3fb24150 (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp@0bfd3fb24150 (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp

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

author: jmasa
date: Tue, 13 Apr 2010 13:52:10 -0700
changeset 1822: 0bfd3fb24150
parent 1717: b81f3572f355
child 1907: c18cbe5936b8
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.
  *
  */
 // Forward decl
 class ConcurrentG1RefineThread;
 class G1RemSet;
 class ConcurrentG1Refine: public CHeapObj {
   ConcurrentG1RefineThread** _threads;
   int _n_threads;
   int _n_worker_threads;
  /*
   * The value of the update buffer queue length falls into one of 3 zones:
   * green, yellow, red. If the value is in [0, green) nothing is
   * done, the buffers are left unprocessed to enable the caching effect of the
   * dirtied cards. In the yellow zone [green, yellow) the concurrent refinement
   * threads are gradually activated. In [yellow, red) all threads are
   * running. If the length becomes red (max queue length) the mutators start
   * processing the buffers.
   *
   * There are some interesting cases (when G1UseAdaptiveConcRefinement
   * is turned off):
   * 1) green = yellow = red = 0. In this case the mutator will process all
   *    buffers. Except for those that are created by the deferred updates
   *    machinery during a collection.
   * 2) green = 0. Means no caching. Can be a good way to minimize the
   *    amount of time spent updating rsets during a collection.
   */
   int _green_zone;
   int _yellow_zone;
   int _red_zone;
   int _thread_threshold_step;
   // Reset the threshold step value based of the current zone boundaries.
   void reset_threshold_step();
   // The cache for card refinement.
   bool   _use_cache;
   bool   _def_use_cache;
   size_t _n_periods;    // Used as clearing epoch
   // An evicting cache of the number of times each card
   // is accessed. Reduces, but does not eliminate, the amount
   // of duplicated processing of dirty cards.
   enum SomePrivateConstants {
     epoch_bits           = 32,
     card_num_shift       = epoch_bits,
     epoch_mask           = AllBits,
     card_num_mask        = AllBits,
     // The initial cache size is approximately this fraction
     // of a maximal cache (i.e. the size needed for all cards
     // in the heap)
     InitialCacheFraction = 512
   };
   const static julong card_num_mask_in_place =
                         (julong) card_num_mask << card_num_shift;
   typedef struct {
     julong _value;      // |  card_num   |  epoch   |
   } CardEpochCacheEntry;
   julong make_epoch_entry(unsigned int card_num, unsigned int epoch) {
     assert(0 <= card_num && card_num < _max_n_card_counts, "Bounds");
     assert(0 <= epoch && epoch <= _n_periods, "must be");
     return ((julong) card_num << card_num_shift) | epoch;
   }
   unsigned int extract_epoch(julong v) {
     return (v & epoch_mask);
   }
   unsigned int extract_card_num(julong v) {
     return (v & card_num_mask_in_place) >> card_num_shift;
   }
   typedef struct {
     unsigned char _count;
     unsigned char _evict_count;
   } CardCountCacheEntry;
   CardCountCacheEntry* _card_counts;
   CardEpochCacheEntry* _card_epochs;
   // The current number of buckets in the card count cache
   unsigned _n_card_counts;
   // The max number of buckets required for the number of
   // cards for the entire reserved heap
   unsigned _max_n_card_counts;
   // Possible sizes of the cache: odd primes that roughly double in size.
   // (See jvmtiTagMap.cpp).
   static int _cc_cache_sizes[];
   // The index in _cc_cache_sizes corresponding to the size of
   // _card_counts.
   int _cache_size_index;
   bool _expand_card_counts;
   const jbyte* _ct_bot;
   jbyte**      _hot_cache;
   int          _hot_cache_size;
   int          _n_hot;
   int          _hot_cache_idx;
   int          _hot_cache_par_chunk_size;
   volatile int _hot_cache_par_claimed_idx;
   // Needed to workaround 6817995
   CardTableModRefBS* _ct_bs;
   G1CollectedHeap*   _g1h;
   // Expands the array that holds the card counts to the next size up
   void expand_card_count_cache();
   // hash a given key (index of card_ptr) with the specified size
   static unsigned int hash(size_t key, int size) {
     return (unsigned int) key % size;
   }
   // hash a given key (index of card_ptr)
   unsigned int hash(size_t key) {
     return hash(key, _n_card_counts);
   }
   unsigned ptr_2_card_num(jbyte* card_ptr) {
     return (unsigned) (card_ptr - _ct_bot);
   }
   jbyte* card_num_2_ptr(unsigned card_num) {
     return (jbyte*) (_ct_bot + card_num);
   }
   // Returns the count of this card after incrementing it.
   jbyte* add_card_count(jbyte* card_ptr, int* count, bool* defer);
   // Returns true if this card is in a young region
   bool is_young_card(jbyte* card_ptr);
  public:
   ConcurrentG1Refine();
   ~ConcurrentG1Refine();
   void init(); // Accomplish some initialization that has to wait.
   void stop();
   void reinitialize_threads();
   // Iterate over the conc refine threads
   void threads_do(ThreadClosure *tc);
   // If this is the first entry for the slot, writes into the cache and
   // returns NULL.  If it causes an eviction, returns the evicted pointer.
   // Otherwise, its a cache hit, and returns NULL.
   jbyte* cache_insert(jbyte* card_ptr, bool* defer);
   // Process the cached entries.
   void clean_up_cache(int worker_i, G1RemSet* g1rs);
   // Set up for parallel processing of the cards in the hot cache
   void clear_hot_cache_claimed_index() {
     _hot_cache_par_claimed_idx = 0;
   }
   // Discard entries in the hot cache.
   void clear_hot_cache() {
     _hot_cache_idx = 0; _n_hot = 0;
   }
   bool hot_cache_is_empty() { return _n_hot == 0; }
   bool use_cache() { return _use_cache; }
   void set_use_cache(bool b) {
     if (b) _use_cache = _def_use_cache;
     else   _use_cache = false;
   }
   void clear_and_record_card_counts();
   static int thread_num();
   void print_worker_threads_on(outputStream* st) const;
   void set_green_zone(int x)  { _green_zone = x;  }
   void set_yellow_zone(int x) { _yellow_zone = x; }
   void set_red_zone(int x)    { _red_zone = x;    }
   int green_zone() const      { return _green_zone;  }
   int yellow_zone() const     { return _yellow_zone; }
   int red_zone() const        { return _red_zone;    }
   int total_thread_num() const  { return _n_threads;        }
   int worker_thread_num() const { return _n_worker_threads; }
   int thread_threshold_step() const { return _thread_threshold_step; }
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp@0bfd3fb24150 (annotated)

src/share/vm/gc_implementation/g1/concurrentG1Refine.hpp