jdk8-mips64-public/hotspot: src/share/vm/memory/genCollectedHeap.hpp@7b0e9cba0307 (annotated)

src/share/vm/memory/genCollectedHeap.hpp@7b0e9cba0307 (annotated)

src/share/vm/memory/genCollectedHeap.hpp

Wed, 13 Jan 2010 15:26:39 -0800

author: ysr
date: Wed, 13 Jan 2010 15:26:39 -0800
changeset 1601: 7b0e9cba0307
parent 1463: 052a899eec3e
child 1907: c18cbe5936b8
permissions: -rw-r--r--

6896647: card marks can be deferred too long
Summary: Deferred card marks are now flushed during the gc prologue. Parallel[Scavege,OldGC] and SerialGC no longer defer card marks generated by COMPILER2 as a result of ReduceInitialCardMarks. For these cases, introduced a diagnostic option to defer the card marks, only for the purposes of testing and diagnostics. CMS and G1 continue to defer card marks. Potential performance concern related to single-threaded flushing of deferred card marks in the gc prologue will be addressed in the future.
Reviewed-by: never, johnc

 /*
  * Copyright 2000-2009 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.
  *
  */
 class SubTasksDone;
 // A "GenCollectedHeap" is a SharedHeap that uses generational
 // collection.  It is represented with a sequence of Generation's.
 class GenCollectedHeap : public SharedHeap {
   friend class GenCollectorPolicy;
   friend class Generation;
   friend class DefNewGeneration;
   friend class TenuredGeneration;
   friend class ConcurrentMarkSweepGeneration;
   friend class CMSCollector;
   friend class GenMarkSweep;
   friend class VM_GenCollectForAllocation;
   friend class VM_GenCollectForPermanentAllocation;
   friend class VM_GenCollectFull;
   friend class VM_GenCollectFullConcurrent;
   friend class VM_GC_HeapInspection;
   friend class VM_HeapDumper;
   friend class HeapInspection;
   friend class GCCauseSetter;
   friend class VMStructs;
 public:
   enum SomeConstants {
     max_gens = 10
   };
   friend class VM_PopulateDumpSharedSpace;
  protected:
   // Fields:
   static GenCollectedHeap* _gch;
  private:
   int _n_gens;
   Generation* _gens[max_gens];
   GenerationSpec** _gen_specs;
   // The generational collector policy.
   GenCollectorPolicy* _gen_policy;
   // If a generation would bail out of an incremental collection,
   // it sets this flag.  If the flag is set, satisfy_failed_allocation
   // will attempt allocating in all generations before doing a full GC.
   bool _incremental_collection_will_fail;
   bool _last_incremental_collection_failed;
   // In support of ExplicitGCInvokesConcurrent functionality
   unsigned int _full_collections_completed;
   // Data structure for claiming the (potentially) parallel tasks in
   // (gen-specific) strong roots processing.
   SubTasksDone* _gen_process_strong_tasks;
   // In block contents verification, the number of header words to skip
   NOT_PRODUCT(static size_t _skip_header_HeapWords;)
   // GC is not allowed during the dump of the shared classes.  Keep track
   // of this in order to provide an reasonable error message when terminating.
   bool _preloading_shared_classes;
 protected:
   // Directs each generation up to and including "collectedGen" to recompute
   // its desired size.
   void compute_new_generation_sizes(int collectedGen);
   // Helper functions for allocation
   HeapWord* attempt_allocation(size_t size,
                                bool   is_tlab,
                                bool   first_only);
   // Helper function for two callbacks below.
   // Considers collection of the first max_level+1 generations.
   void do_collection(bool   full,
                      bool   clear_all_soft_refs,
                      size_t size,
                      bool   is_tlab,
                      int    max_level);
   // Callback from VM_GenCollectForAllocation operation.
   // This function does everything necessary/possible to satisfy an
   // allocation request that failed in the youngest generation that should
   // have handled it (including collection, expansion, etc.)
   HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
   // Callback from VM_GenCollectFull operation.
   // Perform a full collection of the first max_level+1 generations.
   void do_full_collection(bool clear_all_soft_refs, int max_level);
   // Does the "cause" of GC indicate that
   // we absolutely __must__ clear soft refs?
   bool must_clear_all_soft_refs();
 public:
   GenCollectedHeap(GenCollectorPolicy *policy);
   GCStats* gc_stats(int level) const;
   // Returns JNI_OK on success
   virtual jint initialize();
   char* allocate(size_t alignment, PermanentGenerationSpec* perm_gen_spec,
                  size_t* _total_reserved, int* _n_covered_regions,
                  ReservedSpace* heap_rs);
   // Does operations required after initialization has been done.
   void post_initialize();
   // Initialize ("weak") refs processing support
   virtual void ref_processing_init();
   virtual CollectedHeap::Name kind() const {
     return CollectedHeap::GenCollectedHeap;
   }
   // The generational collector policy.
   GenCollectorPolicy* gen_policy() const { return _gen_policy; }
   // Adaptive size policy
   virtual AdaptiveSizePolicy* size_policy() {
     return gen_policy()->size_policy();
   }
   size_t capacity() const;
   size_t used() const;
   // Save the "used_region" for generations level and lower,
   // and, if perm is true, for perm gen.
   void save_used_regions(int level, bool perm);
   size_t max_capacity() const;
   HeapWord* mem_allocate(size_t size,
                          bool   is_large_noref,
                          bool   is_tlab,
                          bool*  gc_overhead_limit_was_exceeded);
   // We may support a shared contiguous allocation area, if the youngest
   // generation does.
   bool supports_inline_contig_alloc() const;
   HeapWord** top_addr() const;
   HeapWord** end_addr() const;
   // Return an estimate of the maximum allocation that could be performed
   // without triggering any collection activity.  In a generational
   // collector, for example, this is probably the largest allocation that
   // could be supported in the youngest generation.  It is "unsafe" because
   // no locks are taken; the result should be treated as an approximation,
   // not a guarantee.
   size_t unsafe_max_alloc();
   // Does this heap support heap inspection? (+PrintClassHistogram)
   virtual bool supports_heap_inspection() const { return true; }
   // Perform a full collection of the heap; intended for use in implementing
   // "System.gc". This implies as full a collection as the CollectedHeap
   // supports. Caller does not hold the Heap_lock on entry.
   void collect(GCCause::Cause cause);
   // This interface assumes that it's being called by the
   // vm thread. It collects the heap assuming that the
   // heap lock is already held and that we are executing in
   // the context of the vm thread.
   void collect_as_vm_thread(GCCause::Cause cause);
   // The same as above but assume that the caller holds the Heap_lock.
   void collect_locked(GCCause::Cause cause);
   // Perform a full collection of the first max_level+1 generations.
   // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
   void collect(GCCause::Cause cause, int max_level);
   // Returns "TRUE" iff "p" points into the allocated area of the heap.
   // The methods is_in(), is_in_closed_subset() and is_in_youngest() may
   // be expensive to compute in general, so, to prevent
   // their inadvertent use in product jvm's, we restrict their use to
   // assertion checking or verification only.
   bool is_in(const void* p) const;
   // override
   bool is_in_closed_subset(const void* p) const {
     if (UseConcMarkSweepGC) {
       return is_in_reserved(p);
     } else {
       return is_in(p);
     }
   }
   // Returns "TRUE" iff "p" points into the youngest generation.
   bool is_in_youngest(void* p);
   // Iteration functions.
   void oop_iterate(OopClosure* cl);
   void oop_iterate(MemRegion mr, OopClosure* cl);
   void object_iterate(ObjectClosure* cl);
   void safe_object_iterate(ObjectClosure* cl);
   void object_iterate_since_last_GC(ObjectClosure* cl);
   Space* space_containing(const void* addr) const;
   // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
   // each address in the (reserved) heap is a member of exactly
   // one block.  The defining characteristic of a block is that it is
   // possible to find its size, and thus to progress forward to the next
   // block.  (Blocks may be of different sizes.)  Thus, blocks may
   // represent Java objects, or they might be free blocks in a
   // free-list-based heap (or subheap), as long as the two kinds are
   // distinguishable and the size of each is determinable.
   // Returns the address of the start of the "block" that contains the
   // address "addr".  We say "blocks" instead of "object" since some heaps
   // may not pack objects densely; a chunk may either be an object or a
   // non-object.
   virtual HeapWord* block_start(const void* addr) const;
   // Requires "addr" to be the start of a chunk, and returns its size.
   // "addr + size" is required to be the start of a new chunk, or the end
   // of the active area of the heap. Assumes (and verifies in non-product
   // builds) that addr is in the allocated part of the heap and is
   // the start of a chunk.
   virtual size_t block_size(const HeapWord* addr) const;
   // Requires "addr" to be the start of a block, and returns "TRUE" iff
   // the block is an object. Assumes (and verifies in non-product
   // builds) that addr is in the allocated part of the heap and is
   // the start of a chunk.
   virtual bool block_is_obj(const HeapWord* addr) const;
   // Section on TLAB's.
   virtual bool supports_tlab_allocation() const;
   virtual size_t tlab_capacity(Thread* thr) const;
   virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
   virtual HeapWord* allocate_new_tlab(size_t size);
   // Can a compiler initialize a new object without store barriers?
   // This permission only extends from the creation of a new object
   // via a TLAB up to the first subsequent safepoint.
   virtual bool can_elide_tlab_store_barriers() const {
     return true;
   }
   virtual bool card_mark_must_follow_store() const {
     return UseConcMarkSweepGC;
   }
   // We don't need barriers for stores to objects in the
   // young gen and, a fortiori, for initializing stores to
   // objects therein. This applies to {DefNew,ParNew}+{Tenured,CMS}
   // only and may need to be re-examined in case other
   // kinds of collectors are implemented in the future.
   virtual bool can_elide_initializing_store_barrier(oop new_obj) {
     // We wanted to assert that:-
     // assert(UseParNewGC || UseSerialGC || UseConcMarkSweepGC,
     //       "Check can_elide_initializing_store_barrier() for this collector");
     // but unfortunately the flag UseSerialGC need not necessarily always
     // be set when DefNew+Tenured are being used.
     return is_in_youngest((void*)new_obj);
   }
   // Can a compiler elide a store barrier when it writes
   // a permanent oop into the heap?  Applies when the compiler
   // is storing x to the heap, where x->is_perm() is true.
   virtual bool can_elide_permanent_oop_store_barriers() const {
     // CMS needs to see all, even intra-generational, ref updates.
     return !UseConcMarkSweepGC;
   }
   // The "requestor" generation is performing some garbage collection
   // action for which it would be useful to have scratch space.  The
   // requestor promises to allocate no more than "max_alloc_words" in any
   // older generation (via promotion say.)   Any blocks of space that can
   // be provided are returned as a list of ScratchBlocks, sorted by
   // decreasing size.
   ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
   // Allow each generation to reset any scratch space that it has
   // contributed as it needs.
   void release_scratch();
   size_t large_typearray_limit();
   // Ensure parsability: override
   virtual void ensure_parsability(bool retire_tlabs);
   // Time in ms since the longest time a collector ran in
   // in any generation.
   virtual jlong millis_since_last_gc();
   // Total number of full collections completed.
   unsigned int total_full_collections_completed() {
     assert(_full_collections_completed <= _total_full_collections,
            "Can't complete more collections than were started");
     return _full_collections_completed;
   }
   // Update above counter, as appropriate, at the end of a stop-world GC cycle
   unsigned int update_full_collections_completed();
   // Update above counter, as appropriate, at the end of a concurrent GC cycle
   unsigned int update_full_collections_completed(unsigned int count);
   // Update "time of last gc" for all constituent generations
   // to "now".
   void update_time_of_last_gc(jlong now) {
     for (int i = 0; i < _n_gens; i++) {
       _gens[i]->update_time_of_last_gc(now);
     }
     perm_gen()->update_time_of_last_gc(now);
   }
   // Update the gc statistics for each generation.
   // "level" is the level of the lastest collection
   void update_gc_stats(int current_level, bool full) {
     for (int i = 0; i < _n_gens; i++) {
       _gens[i]->update_gc_stats(current_level, full);
     }
     perm_gen()->update_gc_stats(current_level, full);
   }
   // Override.
   bool no_gc_in_progress() { return !is_gc_active(); }
   // Override.
   void prepare_for_verify();
   // Override.
   void verify(bool allow_dirty, bool silent, bool /* option */);
   // Override.
   void print() const;
   void print_on(outputStream* st) const;
   virtual void print_gc_threads_on(outputStream* st) const;
   virtual void gc_threads_do(ThreadClosure* tc) const;
   virtual void print_tracing_info() const;
   // PrintGC, PrintGCDetails support
   void print_heap_change(size_t prev_used) const;
   void print_perm_heap_change(size_t perm_prev_used) const;
   // The functions below are helper functions that a subclass of
   // "CollectedHeap" can use in the implementation of its virtual
   // functions.
   class GenClosure : public StackObj {
    public:
     virtual void do_generation(Generation* gen) = 0;
   };
   // Apply "cl.do_generation" to all generations in the heap (not including
   // the permanent generation).  If "old_to_young" determines the order.
   void generation_iterate(GenClosure* cl, bool old_to_young);
   void space_iterate(SpaceClosure* cl);
   // Return "true" if all generations (but perm) have reached the
   // maximal committed limit that they can reach, without a garbage
   // collection.
   virtual bool is_maximal_no_gc() const;
   // Return the generation before "gen", or else NULL.
   Generation* prev_gen(Generation* gen) const {
     int l = gen->level();
     if (l == 0) return NULL;
     else return _gens[l-1];
   }
   // Return the generation after "gen", or else NULL.
   Generation* next_gen(Generation* gen) const {
     int l = gen->level() + 1;
     if (l == _n_gens) return NULL;
     else return _gens[l];
   }
   Generation* get_gen(int i) const {
     if (i >= 0 && i < _n_gens)
       return _gens[i];
     else
       return NULL;
   }
   int n_gens() const {
     assert(_n_gens == gen_policy()->number_of_generations(), "Sanity");
     return _n_gens;
   }
   // Convenience function to be used in situations where the heap type can be
   // asserted to be this type.
   static GenCollectedHeap* heap();
   void set_par_threads(int t);
   // Invoke the "do_oop" method of one of the closures "not_older_gens"
   // or "older_gens" on root locations for the generation at
   // "level".  (The "older_gens" closure is used for scanning references
   // from older generations; "not_older_gens" is used everywhere else.)
   // If "younger_gens_as_roots" is false, younger generations are
   // not scanned as roots; in this case, the caller must be arranging to
   // scan the younger generations itself.  (For example, a generation might
   // explicitly mark reachable objects in younger generations, to avoid
   // excess storage retention.)  If "collecting_perm_gen" is false, then
   // roots that may only contain references to permGen objects are not
   // scanned. The "so" argument determines which of the roots
   // the closure is applied to:
   // "SO_None" does none;
   // "SO_AllClasses" applies the closure to all entries in the SystemDictionary;
   // "SO_SystemClasses" to all the "system" classes and loaders;
   // "SO_Symbols_and_Strings" applies the closure to all entries in
   // SymbolsTable and StringTable.
   void gen_process_strong_roots(int level,
                                 bool younger_gens_as_roots,
                                 // The remaining arguments are in an order
                                 // consistent with SharedHeap::process_strong_roots:
                                 bool activate_scope,
                                 bool collecting_perm_gen,
                                 SharedHeap::ScanningOption so,
                                 OopsInGenClosure* not_older_gens,
                                 bool do_code_roots,
                                 OopsInGenClosure* older_gens);
   // Apply "blk" to all the weak roots of the system.  These include
   // JNI weak roots, the code cache, system dictionary, symbol table,
   // string table, and referents of reachable weak refs.
   void gen_process_weak_roots(OopClosure* root_closure,
                               CodeBlobClosure* code_roots,
                               OopClosure* non_root_closure);
   // Set the saved marks of generations, if that makes sense.
   // In particular, if any generation might iterate over the oops
   // in other generations, it should call this method.
   void save_marks();
   // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects
   // allocated since the last call to save_marks in generations at or above
   // "level" (including the permanent generation.)  The "cur" closure is
   // applied to references in the generation at "level", and the "older"
   // closure to older (and permanent) generations.
 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix)    \
   void oop_since_save_marks_iterate(int level,                          \
                                     OopClosureType* cur,                \
                                     OopClosureType* older);
   ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL)
 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL
   // Returns "true" iff no allocations have occurred in any generation at
   // "level" or above (including the permanent generation) since the last
   // call to "save_marks".
   bool no_allocs_since_save_marks(int level);
   // If a generation bails out of an incremental collection,
   // it sets this flag.
   bool incremental_collection_will_fail() {
     return _incremental_collection_will_fail;
   }
   void set_incremental_collection_will_fail() {
     _incremental_collection_will_fail = true;
   }
   void clear_incremental_collection_will_fail() {
     _incremental_collection_will_fail = false;
   }
   bool last_incremental_collection_failed() const {
     return _last_incremental_collection_failed;
   }
   void set_last_incremental_collection_failed() {
     _last_incremental_collection_failed = true;
   }
   void clear_last_incremental_collection_failed() {
     _last_incremental_collection_failed = false;
   }
   // Promotion of obj into gen failed.  Try to promote obj to higher non-perm
   // gens in ascending order; return the new location of obj if successful.
   // Otherwise, try expand-and-allocate for obj in each generation starting at
   // gen; return the new location of obj if successful.  Otherwise, return NULL.
   oop handle_failed_promotion(Generation* gen,
                               oop obj,
                               size_t obj_size);
 private:
   // Accessor for memory state verification support
   NOT_PRODUCT(
     static size_t skip_header_HeapWords() { return _skip_header_HeapWords; }
   )
   // Override
   void check_for_non_bad_heap_word_value(HeapWord* addr,
     size_t size) PRODUCT_RETURN;
   // For use by mark-sweep.  As implemented, mark-sweep-compact is global
   // in an essential way: compaction is performed across generations, by
   // iterating over spaces.
   void prepare_for_compaction();
   // Perform a full collection of the first max_level+1 generations.
   // This is the low level interface used by the public versions of
   // collect() and collect_locked(). Caller holds the Heap_lock on entry.
   void collect_locked(GCCause::Cause cause, int max_level);
   // Returns success or failure.
   bool create_cms_collector();
   // In support of ExplicitGCInvokesConcurrent functionality
   bool should_do_concurrent_full_gc(GCCause::Cause cause);
   void collect_mostly_concurrent(GCCause::Cause cause);
   // Save the tops of the spaces in all generations
   void record_gen_tops_before_GC() PRODUCT_RETURN;
 protected:
   virtual void gc_prologue(bool full);
   virtual void gc_epilogue(bool full);
 public:
   virtual void preload_and_dump(TRAPS) KERNEL_RETURN;
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/genCollectedHeap.hpp@7b0e9cba0307 (annotated)

src/share/vm/memory/genCollectedHeap.hpp