--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,388 @@
+/*
+ * Copyright 2001-2007 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 ChunkArray;
+class ParScanWithoutBarrierClosure;
+class ParScanWithBarrierClosure;
+class ParRootScanWithoutBarrierClosure;
+class ParRootScanWithBarrierTwoGensClosure;
+class ParEvacuateFollowersClosure;
+
+// It would be better if these types could be kept local to the .cpp file,
+// but they must be here to allow ParScanClosure::do_oop_work to be defined
+// in genOopClosures.inline.hpp.
+
+
+typedef OopTaskQueue ObjToScanQueue;
+typedef OopTaskQueueSet ObjToScanQueueSet;
+
+// Enable this to get push/pop/steal stats.
+const int PAR_STATS_ENABLED = 0;
+
+class ParKeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
+ ParScanWeakRefClosure* _par_cl;
+ public:
+ ParKeepAliveClosure(ParScanWeakRefClosure* cl);
+ void do_oop(oop* p);
+};
+
+// The state needed by thread performing parallel young-gen collection.
+class ParScanThreadState {
+ friend class ParScanThreadStateSet;
+ ObjToScanQueue *_work_queue;
+
+ ParGCAllocBuffer _to_space_alloc_buffer;
+
+ ParScanWithoutBarrierClosure _to_space_closure; // scan_without_gc_barrier
+ ParScanWithBarrierClosure _old_gen_closure; // scan_with_gc_barrier
+ ParRootScanWithoutBarrierClosure _to_space_root_closure; // scan_root_without_gc_barrier
+ // One of these two will be passed to process_strong_roots, which will
+ // set its generation. The first is for two-gen configs where the
+ // old gen collects the perm gen; the second is for arbitrary configs.
+ // The second isn't used right now (it used to be used for the train, an
+ // incremental collector) but the declaration has been left as a reminder.
+ ParRootScanWithBarrierTwoGensClosure _older_gen_closure;
+ // This closure will always be bound to the old gen; it will be used
+ // in evacuate_followers.
+ ParRootScanWithBarrierTwoGensClosure _old_gen_root_closure; // scan_old_root_with_gc_barrier
+ ParEvacuateFollowersClosure _evacuate_followers;
+ DefNewGeneration::IsAliveClosure _is_alive_closure;
+ ParScanWeakRefClosure _scan_weak_ref_closure;
+ ParKeepAliveClosure _keep_alive_closure;
+
+
+ Space* _to_space;
+ Space* to_space() { return _to_space; }
+
+ Generation* _old_gen;
+ Generation* old_gen() { return _old_gen; }
+
+ HeapWord *_young_old_boundary;
+
+ int _hash_seed;
+ int _thread_num;
+ ageTable _ageTable;
+
+ bool _to_space_full;
+
+ int _pushes, _pops, _steals, _steal_attempts, _term_attempts;
+ int _overflow_pushes, _overflow_refills, _overflow_refill_objs;
+
+ // Timing numbers.
+ double _start;
+ double _start_strong_roots;
+ double _strong_roots_time;
+ double _start_term;
+ double _term_time;
+
+ // Helper for trim_queues. Scans subset of an array and makes
+ // remainder available for work stealing.
+ void scan_partial_array_and_push_remainder(oop obj);
+
+ // In support of CMS' parallel rescan of survivor space.
+ ChunkArray* _survivor_chunk_array;
+ ChunkArray* survivor_chunk_array() { return _survivor_chunk_array; }
+
+ void record_survivor_plab(HeapWord* plab_start, size_t plab_word_size);
+
+ ParScanThreadState(Space* to_space_, ParNewGeneration* gen_,
+ Generation* old_gen_, int thread_num_,
+ ObjToScanQueueSet* work_queue_set_, size_t desired_plab_sz_,
+ ParallelTaskTerminator& term_);
+
+public:
+ ageTable* age_table() {return &_ageTable;}
+
+ ObjToScanQueue* work_queue() { return _work_queue; }
+
+ ParGCAllocBuffer* to_space_alloc_buffer() {
+ return &_to_space_alloc_buffer;
+ }
+
+ ParEvacuateFollowersClosure& evacuate_followers_closure() { return _evacuate_followers; }
+ DefNewGeneration::IsAliveClosure& is_alive_closure() { return _is_alive_closure; }
+ ParScanWeakRefClosure& scan_weak_ref_closure() { return _scan_weak_ref_closure; }
+ ParKeepAliveClosure& keep_alive_closure() { return _keep_alive_closure; }
+ ParScanClosure& older_gen_closure() { return _older_gen_closure; }
+ ParRootScanWithoutBarrierClosure& to_space_root_closure() { return _to_space_root_closure; };
+
+ // Decrease queue size below "max_size".
+ void trim_queues(int max_size);
+
+ // Is new_obj a candidate for scan_partial_array_and_push_remainder method.
+ inline bool should_be_partially_scanned(oop new_obj, oop old_obj) const;
+
+ int* hash_seed() { return &_hash_seed; }
+ int thread_num() { return _thread_num; }
+
+ // Allocate a to-space block of size "sz", or else return NULL.
+ HeapWord* alloc_in_to_space_slow(size_t word_sz);
+
+ HeapWord* alloc_in_to_space(size_t word_sz) {
+ HeapWord* obj = to_space_alloc_buffer()->allocate(word_sz);
+ if (obj != NULL) return obj;
+ else return alloc_in_to_space_slow(word_sz);
+ }
+
+ HeapWord* young_old_boundary() { return _young_old_boundary; }
+
+ void set_young_old_boundary(HeapWord *boundary) {
+ _young_old_boundary = boundary;
+ }
+
+ // Undo the most recent allocation ("obj", of "word_sz").
+ void undo_alloc_in_to_space(HeapWord* obj, size_t word_sz);
+
+ int pushes() { return _pushes; }
+ int pops() { return _pops; }
+ int steals() { return _steals; }
+ int steal_attempts() { return _steal_attempts; }
+ int term_attempts() { return _term_attempts; }
+ int overflow_pushes() { return _overflow_pushes; }
+ int overflow_refills() { return _overflow_refills; }
+ int overflow_refill_objs() { return _overflow_refill_objs; }
+
+ void note_push() { if (PAR_STATS_ENABLED) _pushes++; }
+ void note_pop() { if (PAR_STATS_ENABLED) _pops++; }
+ void note_steal() { if (PAR_STATS_ENABLED) _steals++; }
+ void note_steal_attempt() { if (PAR_STATS_ENABLED) _steal_attempts++; }
+ void note_term_attempt() { if (PAR_STATS_ENABLED) _term_attempts++; }
+ void note_overflow_push() { if (PAR_STATS_ENABLED) _overflow_pushes++; }
+ void note_overflow_refill(int objs) {
+ if (PAR_STATS_ENABLED) {
+ _overflow_refills++;
+ _overflow_refill_objs += objs;
+ }
+ }
+
+ void start_strong_roots() {
+ _start_strong_roots = os::elapsedTime();
+ }
+ void end_strong_roots() {
+ _strong_roots_time += (os::elapsedTime() - _start_strong_roots);
+ }
+ double strong_roots_time() { return _strong_roots_time; }
+ void start_term_time() {
+ note_term_attempt();
+ _start_term = os::elapsedTime();
+ }
+ void end_term_time() {
+ _term_time += (os::elapsedTime() - _start_term);
+ }
+ double term_time() { return _term_time; }
+
+ double elapsed() {
+ return os::elapsedTime() - _start;
+ }
+
+};
+
+class ParNewGenTask: public AbstractGangTask {
+ ParNewGeneration* _gen;
+ Generation* _next_gen;
+ HeapWord* _young_old_boundary;
+ class ParScanThreadStateSet* _state_set;
+
+public:
+ ParNewGenTask(ParNewGeneration* gen,
+ Generation* next_gen,
+ HeapWord* young_old_boundary,
+ ParScanThreadStateSet* state_set);
+
+ HeapWord* young_old_boundary() { return _young_old_boundary; }
+
+ void work(int i);
+};
+
+class KeepAliveClosure: public DefNewGeneration::KeepAliveClosure {
+ public:
+ KeepAliveClosure(ScanWeakRefClosure* cl);
+ void do_oop(oop* p);
+};
+
+class EvacuateFollowersClosureGeneral: public VoidClosure {
+ GenCollectedHeap* _gch;
+ int _level;
+ OopsInGenClosure* _scan_cur_or_nonheap;
+ OopsInGenClosure* _scan_older;
+ public:
+ EvacuateFollowersClosureGeneral(GenCollectedHeap* gch, int level,
+ OopsInGenClosure* cur,
+ OopsInGenClosure* older);
+ void do_void();
+};
+
+// Closure for scanning ParNewGeneration.
+// Same as ScanClosure, except does parallel GC barrier.
+class ScanClosureWithParBarrier: public ScanClosure {
+public:
+ ScanClosureWithParBarrier(ParNewGeneration* g, bool gc_barrier);
+ void do_oop(oop* p);
+};
+
+// Implements AbstractRefProcTaskExecutor for ParNew.
+class ParNewRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
+public:
+
+ ParNewRefProcTaskExecutor(ParNewGeneration& generation,
+ ParScanThreadStateSet& state_set)
+ : _generation(generation), _state_set(state_set)
+ { }
+
+ // Executes a task using worker threads.
+ virtual void execute(ProcessTask& task);
+ virtual void execute(EnqueueTask& task);
+ // Switch to single threaded mode.
+ virtual void set_single_threaded_mode();
+private:
+ ParNewGeneration& _generation;
+ ParScanThreadStateSet& _state_set;
+};
+
+
+// A Generation that does parallel young-gen collection.
+
+class ParNewGeneration: public DefNewGeneration {
+ friend class ParNewGenTask;
+ friend class ParNewRefProcTask;
+ friend class ParNewRefProcTaskExecutor;
+ friend class ParScanThreadStateSet;
+
+ // XXX use a global constant instead of 64!
+ struct ObjToScanQueuePadded {
+ ObjToScanQueue work_queue;
+ char pad[64 - sizeof(ObjToScanQueue)]; // prevent false sharing
+ };
+
+ // The per-thread work queues, available here for stealing.
+ ObjToScanQueueSet* _task_queues;
+
+ // Desired size of survivor space plab's
+ PLABStats _plab_stats;
+
+ // A list of from-space images of to-be-scanned objects, threaded through
+ // klass-pointers (klass information already copied to the forwarded
+ // image.) Manipulated with CAS.
+ oop _overflow_list;
+
+ // If true, older generation does not support promotion undo, so avoid.
+ static bool _avoid_promotion_undo;
+
+ // This closure is used by the reference processor to filter out
+ // references to live referent.
+ DefNewGeneration::IsAliveClosure _is_alive_closure;
+
+ static oop real_forwardee_slow(oop obj);
+ static void waste_some_time();
+
+ // Preserve the mark of "obj", if necessary, in preparation for its mark
+ // word being overwritten with a self-forwarding-pointer.
+ void preserve_mark_if_necessary(oop obj, markOop m);
+
+ protected:
+
+ bool _survivor_overflow;
+
+ bool avoid_promotion_undo() { return _avoid_promotion_undo; }
+ void set_avoid_promotion_undo(bool v) { _avoid_promotion_undo = v; }
+
+ bool survivor_overflow() { return _survivor_overflow; }
+ void set_survivor_overflow(bool v) { _survivor_overflow = v; }
+
+ // Adjust the tenuring threshold. See the implementation for
+ // the details of the policy.
+ virtual void adjust_desired_tenuring_threshold();
+
+public:
+ ParNewGeneration(ReservedSpace rs, size_t initial_byte_size, int level);
+
+ ~ParNewGeneration() {
+ for (uint i = 0; i < ParallelGCThreads; i++)
+ delete _task_queues->queue(i);
+
+ delete _task_queues;
+ }
+
+ virtual void ref_processor_init();
+ virtual Generation::Name kind() { return Generation::ParNew; }
+ virtual const char* name() const;
+ virtual const char* short_name() const { return "ParNew"; }
+
+ // override
+ virtual bool refs_discovery_is_mt() const {
+ assert(UseParNewGC, "ParNewGeneration only when UseParNewGC");
+ return ParallelGCThreads > 1;
+ }
+
+ // Make the collection virtual.
+ virtual void collect(bool full,
+ bool clear_all_soft_refs,
+ size_t size,
+ bool is_tlab);
+
+ // This needs to be visible to the closure function.
+ // "obj" is the object to be copied, "m" is a recent value of its mark
+ // that must not contain a forwarding pointer (though one might be
+ // inserted in "obj"s mark word by a parallel thread).
+ inline oop copy_to_survivor_space(ParScanThreadState* par_scan_state,
+ oop obj, size_t obj_sz, markOop m) {
+ if (_avoid_promotion_undo) {
+ return copy_to_survivor_space_avoiding_promotion_undo(par_scan_state,
+ obj, obj_sz, m);
+ }
+
+ return copy_to_survivor_space_with_undo(par_scan_state, obj, obj_sz, m);
+ }
+
+ oop copy_to_survivor_space_avoiding_promotion_undo(ParScanThreadState* par_scan_state,
+ oop obj, size_t obj_sz, markOop m);
+
+ oop copy_to_survivor_space_with_undo(ParScanThreadState* par_scan_state,
+ oop obj, size_t obj_sz, markOop m);
+
+ // Push the given (from-space) object on the global overflow list.
+ void push_on_overflow_list(oop from_space_obj);
+
+ // If the global overflow list is non-empty, move some tasks from it
+ // onto "work_q" (which must be empty). No more than 1/4 of the
+ // max_elems of "work_q" are moved.
+ bool take_from_overflow_list(ParScanThreadState* par_scan_state);
+
+ // The task queues to be used by parallel GC threads.
+ ObjToScanQueueSet* task_queues() {
+ return _task_queues;
+ }
+
+ PLABStats* plab_stats() {
+ return &_plab_stats;
+ }
+
+ size_t desired_plab_sz() {
+ return _plab_stats.desired_plab_sz();
+ }
+
+ static oop real_forwardee(oop obj);
+
+ DEBUG_ONLY(static bool is_legal_forward_ptr(oop p);)
+};