--- a/src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.hpp Fri Nov 08 14:54:17 2019 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,1796 +0,0 @@
-/*
- * Copyright (c) 2001, 2019, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
-
-#ifndef SHARE_GC_CMS_CONCURRENTMARKSWEEPGENERATION_HPP
-#define SHARE_GC_CMS_CONCURRENTMARKSWEEPGENERATION_HPP
-
-#include "gc/cms/cmsOopClosures.hpp"
-#include "gc/cms/gSpaceCounters.hpp"
-#include "gc/cms/yieldingWorkgroup.hpp"
-#include "gc/shared/cardGeneration.hpp"
-#include "gc/shared/gcHeapSummary.hpp"
-#include "gc/shared/gcStats.hpp"
-#include "gc/shared/gcWhen.hpp"
-#include "gc/shared/generationCounters.hpp"
-#include "gc/shared/space.hpp"
-#include "gc/shared/taskqueue.hpp"
-#include "logging/log.hpp"
-#include "memory/iterator.hpp"
-#include "memory/virtualspace.hpp"
-#include "runtime/mutexLocker.hpp"
-#include "services/memoryService.hpp"
-#include "utilities/bitMap.hpp"
-#include "utilities/stack.hpp"
-
-// ConcurrentMarkSweepGeneration is in support of a concurrent
-// mark-sweep old generation in the Detlefs-Printezis--Boehm-Demers-Schenker
-// style. We assume, for now, that this generation is always the
-// seniormost generation and for simplicity
-// in the first implementation, that this generation is a single compactible
-// space. Neither of these restrictions appears essential, and will be
-// relaxed in the future when more time is available to implement the
-// greater generality (and there's a need for it).
-//
-// Concurrent mode failures are currently handled by
-// means of a sliding mark-compact.
-
-class AdaptiveSizePolicy;
-class CMSCollector;
-class CMSConcMarkingTask;
-class CMSGCAdaptivePolicyCounters;
-class CMSTracer;
-class ConcurrentGCTimer;
-class ConcurrentMarkSweepGeneration;
-class ConcurrentMarkSweepPolicy;
-class ConcurrentMarkSweepThread;
-class CompactibleFreeListSpace;
-class FreeChunk;
-class ParNewGeneration;
-class PromotionInfo;
-class ScanMarkedObjectsAgainCarefullyClosure;
-class SerialOldTracer;
-
-// A generic CMS bit map. It's the basis for both the CMS marking bit map
-// as well as for the mod union table (in each case only a subset of the
-// methods are used). This is essentially a wrapper around the BitMap class,
-// with one bit per (1<<_shifter) HeapWords. (i.e. for the marking bit map,
-// we have _shifter == 0. and for the mod union table we have
-// shifter == CardTable::card_shift - LogHeapWordSize.)
-// XXX 64-bit issues in BitMap?
-class CMSBitMap {
- friend class VMStructs;
-
- HeapWord* _bmStartWord; // base address of range covered by map
- size_t _bmWordSize; // map size (in #HeapWords covered)
- const int _shifter; // shifts to convert HeapWord to bit position
- VirtualSpace _virtual_space; // underlying the bit map
- BitMapView _bm; // the bit map itself
- Mutex* const _lock; // mutex protecting _bm;
-
- public:
- // constructor
- CMSBitMap(int shifter, int mutex_rank, const char* mutex_name);
-
- // allocates the actual storage for the map
- bool allocate(MemRegion mr);
- // field getter
- Mutex* lock() const { return _lock; }
- // locking verifier convenience function
- void assert_locked() const PRODUCT_RETURN;
-
- // inquiries
- HeapWord* startWord() const { return _bmStartWord; }
- size_t sizeInWords() const { return _bmWordSize; }
- size_t sizeInBits() const { return _bm.size(); }
- // the following is one past the last word in space
- HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
-
- // reading marks
- bool isMarked(HeapWord* addr) const;
- bool par_isMarked(HeapWord* addr) const; // do not lock checks
- bool isUnmarked(HeapWord* addr) const;
- bool isAllClear() const;
-
- // writing marks
- void mark(HeapWord* addr);
- // For marking by parallel GC threads;
- // returns true if we did, false if another thread did
- bool par_mark(HeapWord* addr);
-
- void mark_range(MemRegion mr);
- void par_mark_range(MemRegion mr);
- void mark_large_range(MemRegion mr);
- void par_mark_large_range(MemRegion mr);
- void par_clear(HeapWord* addr); // For unmarking by parallel GC threads.
- void clear_range(MemRegion mr);
- void par_clear_range(MemRegion mr);
- void clear_large_range(MemRegion mr);
- void par_clear_large_range(MemRegion mr);
- void clear_all();
- void clear_all_incrementally(); // Not yet implemented!!
-
- NOT_PRODUCT(
- // checks the memory region for validity
- void region_invariant(MemRegion mr);
- )
-
- // iteration
- void iterate(BitMapClosure* cl) {
- _bm.iterate(cl);
- }
- void iterate(BitMapClosure* cl, HeapWord* left, HeapWord* right);
- void dirty_range_iterate_clear(MemRegionClosure* cl);
- void dirty_range_iterate_clear(MemRegion mr, MemRegionClosure* cl);
-
- // auxiliary support for iteration
- HeapWord* getNextMarkedWordAddress(HeapWord* addr) const;
- HeapWord* getNextMarkedWordAddress(HeapWord* start_addr,
- HeapWord* end_addr) const;
- HeapWord* getNextUnmarkedWordAddress(HeapWord* addr) const;
- HeapWord* getNextUnmarkedWordAddress(HeapWord* start_addr,
- HeapWord* end_addr) const;
- MemRegion getAndClearMarkedRegion(HeapWord* addr);
- MemRegion getAndClearMarkedRegion(HeapWord* start_addr,
- HeapWord* end_addr);
-
- // conversion utilities
- HeapWord* offsetToHeapWord(size_t offset) const;
- size_t heapWordToOffset(HeapWord* addr) const;
- size_t heapWordDiffToOffsetDiff(size_t diff) const;
-
- void print_on_error(outputStream* st, const char* prefix) const;
-
- // debugging
- // is this address range covered by the bit-map?
- NOT_PRODUCT(
- bool covers(MemRegion mr) const;
- bool covers(HeapWord* start, size_t size = 0) const;
- )
- void verifyNoOneBitsInRange(HeapWord* left, HeapWord* right) PRODUCT_RETURN;
-};
-
-// Represents a marking stack used by the CMS collector.
-// Ideally this should be GrowableArray<> just like MSC's marking stack(s).
-class CMSMarkStack: public CHeapObj<mtGC> {
- friend class CMSCollector; // To get at expansion stats further below.
-
- VirtualSpace _virtual_space; // Space for the stack
- oop* _base; // Bottom of stack
- size_t _index; // One more than last occupied index
- size_t _capacity; // Max #elements
- Mutex _par_lock; // An advisory lock used in case of parallel access
- NOT_PRODUCT(size_t _max_depth;) // Max depth plumbed during run
-
- protected:
- size_t _hit_limit; // We hit max stack size limit
- size_t _failed_double; // We failed expansion before hitting limit
-
- public:
- CMSMarkStack():
- _par_lock(Mutex::event, "CMSMarkStack._par_lock", true,
- Monitor::_safepoint_check_never),
- _hit_limit(0),
- _failed_double(0) {}
-
- bool allocate(size_t size);
-
- size_t capacity() const { return _capacity; }
-
- oop pop() {
- if (!isEmpty()) {
- return _base[--_index] ;
- }
- return NULL;
- }
-
- bool push(oop ptr) {
- if (isFull()) {
- return false;
- } else {
- _base[_index++] = ptr;
- NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));
- return true;
- }
- }
-
- bool isEmpty() const { return _index == 0; }
- bool isFull() const {
- assert(_index <= _capacity, "buffer overflow");
- return _index == _capacity;
- }
-
- size_t length() { return _index; }
-
- // "Parallel versions" of some of the above
- oop par_pop() {
- // lock and pop
- MutexLocker x(&_par_lock, Mutex::_no_safepoint_check_flag);
- return pop();
- }
-
- bool par_push(oop ptr) {
- // lock and push
- MutexLocker x(&_par_lock, Mutex::_no_safepoint_check_flag);
- return push(ptr);
- }
-
- // Forcibly reset the stack, losing all of its contents.
- void reset() {
- _index = 0;
- }
-
- // Expand the stack, typically in response to an overflow condition.
- void expand();
-
- // Compute the least valued stack element.
- oop least_value(HeapWord* low) {
- HeapWord* least = low;
- for (size_t i = 0; i < _index; i++) {
- least = MIN2(least, (HeapWord*)_base[i]);
- }
- return (oop)least;
- }
-
- // Exposed here to allow stack expansion in || case.
- Mutex* par_lock() { return &_par_lock; }
-};
-
-class CardTableRS;
-class CMSParGCThreadState;
-
-class ModUnionClosure: public MemRegionClosure {
- protected:
- CMSBitMap* _t;
- public:
- ModUnionClosure(CMSBitMap* t): _t(t) { }
- void do_MemRegion(MemRegion mr);
-};
-
-class ModUnionClosurePar: public ModUnionClosure {
- public:
- ModUnionClosurePar(CMSBitMap* t): ModUnionClosure(t) { }
- void do_MemRegion(MemRegion mr);
-};
-
-// Survivor Chunk Array in support of parallelization of
-// Survivor Space rescan.
-class ChunkArray: public CHeapObj<mtGC> {
- size_t _index;
- size_t _capacity;
- size_t _overflows;
- HeapWord** _array; // storage for array
-
- public:
- ChunkArray() : _index(0), _capacity(0), _overflows(0), _array(NULL) {}
- ChunkArray(HeapWord** a, size_t c):
- _index(0), _capacity(c), _overflows(0), _array(a) {}
-
- HeapWord** array() { return _array; }
- void set_array(HeapWord** a) { _array = a; }
-
- size_t capacity() { return _capacity; }
- void set_capacity(size_t c) { _capacity = c; }
-
- size_t end() {
- assert(_index <= capacity(),
- "_index (" SIZE_FORMAT ") > _capacity (" SIZE_FORMAT "): out of bounds",
- _index, _capacity);
- return _index;
- } // exclusive
-
- HeapWord* nth(size_t n) {
- assert(n < end(), "Out of bounds access");
- return _array[n];
- }
-
- void reset() {
- _index = 0;
- if (_overflows > 0) {
- log_trace(gc)("CMS: ChunkArray[" SIZE_FORMAT "] overflowed " SIZE_FORMAT " times", _capacity, _overflows);
- }
- _overflows = 0;
- }
-
- void record_sample(HeapWord* p, size_t sz) {
- // For now we do not do anything with the size
- if (_index < _capacity) {
- _array[_index++] = p;
- } else {
- ++_overflows;
- assert(_index == _capacity,
- "_index (" SIZE_FORMAT ") > _capacity (" SIZE_FORMAT
- "): out of bounds at overflow#" SIZE_FORMAT,
- _index, _capacity, _overflows);
- }
- }
-};
-
-//
-// Timing, allocation and promotion statistics for gc scheduling and incremental
-// mode pacing. Most statistics are exponential averages.
-//
-class CMSStats {
- private:
- ConcurrentMarkSweepGeneration* const _cms_gen; // The cms (old) gen.
-
- // The following are exponential averages with factor alpha:
- // avg = (100 - alpha) * avg + alpha * cur_sample
- //
- // The durations measure: end_time[n] - start_time[n]
- // The periods measure: start_time[n] - start_time[n-1]
- //
- // The cms period and duration include only concurrent collections; time spent
- // in foreground cms collections due to System.gc() or because of a failure to
- // keep up are not included.
- //
- // There are 3 alphas to "bootstrap" the statistics. The _saved_alpha is the
- // real value, but is used only after the first period. A value of 100 is
- // used for the first sample so it gets the entire weight.
- unsigned int _saved_alpha; // 0-100
- unsigned int _gc0_alpha;
- unsigned int _cms_alpha;
-
- double _gc0_duration;
- double _gc0_period;
- size_t _gc0_promoted; // bytes promoted per gc0
- double _cms_duration;
- double _cms_duration_pre_sweep; // time from initiation to start of sweep
- double _cms_period;
- size_t _cms_allocated; // bytes of direct allocation per gc0 period
-
- // Timers.
- elapsedTimer _cms_timer;
- TimeStamp _gc0_begin_time;
- TimeStamp _cms_begin_time;
- TimeStamp _cms_end_time;
-
- // Snapshots of the amount used in the CMS generation.
- size_t _cms_used_at_gc0_begin;
- size_t _cms_used_at_gc0_end;
- size_t _cms_used_at_cms_begin;
-
- // Used to prevent the duty cycle from being reduced in the middle of a cms
- // cycle.
- bool _allow_duty_cycle_reduction;
-
- enum {
- _GC0_VALID = 0x1,
- _CMS_VALID = 0x2,
- _ALL_VALID = _GC0_VALID | _CMS_VALID
- };
-
- unsigned int _valid_bits;
-
- protected:
- // In support of adjusting of cms trigger ratios based on history
- // of concurrent mode failure.
- double cms_free_adjustment_factor(size_t free) const;
- void adjust_cms_free_adjustment_factor(bool fail, size_t free);
-
- public:
- CMSStats(ConcurrentMarkSweepGeneration* cms_gen,
- unsigned int alpha = CMSExpAvgFactor);
-
- // Whether or not the statistics contain valid data; higher level statistics
- // cannot be called until this returns true (they require at least one young
- // gen and one cms cycle to have completed).
- bool valid() const;
-
- // Record statistics.
- void record_gc0_begin();
- void record_gc0_end(size_t cms_gen_bytes_used);
- void record_cms_begin();
- void record_cms_end();
-
- // Allow management of the cms timer, which must be stopped/started around
- // yield points.
- elapsedTimer& cms_timer() { return _cms_timer; }
- void start_cms_timer() { _cms_timer.start(); }
- void stop_cms_timer() { _cms_timer.stop(); }
-
- // Basic statistics; units are seconds or bytes.
- double gc0_period() const { return _gc0_period; }
- double gc0_duration() const { return _gc0_duration; }
- size_t gc0_promoted() const { return _gc0_promoted; }
- double cms_period() const { return _cms_period; }
- double cms_duration() const { return _cms_duration; }
- size_t cms_allocated() const { return _cms_allocated; }
-
- size_t cms_used_at_gc0_end() const { return _cms_used_at_gc0_end;}
-
- // Seconds since the last background cms cycle began or ended.
- double cms_time_since_begin() const;
- double cms_time_since_end() const;
-
- // Higher level statistics--caller must check that valid() returns true before
- // calling.
-
- // Returns bytes promoted per second of wall clock time.
- double promotion_rate() const;
-
- // Returns bytes directly allocated per second of wall clock time.
- double cms_allocation_rate() const;
-
- // Rate at which space in the cms generation is being consumed (sum of the
- // above two).
- double cms_consumption_rate() const;
-
- // Returns an estimate of the number of seconds until the cms generation will
- // fill up, assuming no collection work is done.
- double time_until_cms_gen_full() const;
-
- // Returns an estimate of the number of seconds remaining until
- // the cms generation collection should start.
- double time_until_cms_start() const;
-
- // End of higher level statistics.
-
- // Debugging.
- void print_on(outputStream* st) const PRODUCT_RETURN;
- void print() const { print_on(tty); }
-};
-
-// A closure related to weak references processing which
-// we embed in the CMSCollector, since we need to pass
-// it to the reference processor for secondary filtering
-// of references based on reachability of referent;
-// see role of _is_alive_non_header closure in the
-// ReferenceProcessor class.
-// For objects in the CMS generation, this closure checks
-// if the object is "live" (reachable). Used in weak
-// reference processing.
-class CMSIsAliveClosure: public BoolObjectClosure {
- const MemRegion _span;
- const CMSBitMap* _bit_map;
-
- friend class CMSCollector;
- public:
- CMSIsAliveClosure(MemRegion span,
- CMSBitMap* bit_map):
- _span(span),
- _bit_map(bit_map) {
- assert(!span.is_empty(), "Empty span could spell trouble");
- }
-
- bool do_object_b(oop obj);
-};
-
-
-// Implements AbstractRefProcTaskExecutor for CMS.
-class CMSRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
-public:
-
- CMSRefProcTaskExecutor(CMSCollector& collector)
- : _collector(collector)
- { }
-
- // Executes a task using worker threads.
- virtual void execute(ProcessTask& task, uint ergo_workers);
-private:
- CMSCollector& _collector;
-};
-
-
-class CMSCollector: public CHeapObj<mtGC> {
- friend class VMStructs;
- friend class ConcurrentMarkSweepThread;
- friend class ConcurrentMarkSweepGeneration;
- friend class CompactibleFreeListSpace;
- friend class CMSParMarkTask;
- friend class CMSParInitialMarkTask;
- friend class CMSParRemarkTask;
- friend class CMSConcMarkingTask;
- friend class CMSRefProcTaskProxy;
- friend class CMSRefProcTaskExecutor;
- friend class ScanMarkedObjectsAgainCarefullyClosure; // for sampling eden
- friend class SurvivorSpacePrecleanClosure; // --- ditto -------
- friend class PushOrMarkClosure; // to access _restart_addr
- friend class ParPushOrMarkClosure; // to access _restart_addr
- friend class MarkFromRootsClosure; // -- ditto --
- // ... and for clearing cards
- friend class ParMarkFromRootsClosure; // to access _restart_addr
- // ... and for clearing cards
- friend class ParConcMarkingClosure; // to access _restart_addr etc.
- friend class MarkFromRootsVerifyClosure; // to access _restart_addr
- friend class PushAndMarkVerifyClosure; // -- ditto --
- friend class MarkRefsIntoAndScanClosure; // to access _overflow_list
- friend class PushAndMarkClosure; // -- ditto --
- friend class ParPushAndMarkClosure; // -- ditto --
- friend class CMSKeepAliveClosure; // -- ditto --
- friend class CMSDrainMarkingStackClosure; // -- ditto --
- friend class CMSInnerParMarkAndPushClosure; // -- ditto --
- NOT_PRODUCT(friend class ScanMarkedObjectsAgainClosure;) // assertion on _overflow_list
- friend class ReleaseForegroundGC; // to access _foregroundGCShouldWait
- friend class VM_CMS_Operation;
- friend class VM_CMS_Initial_Mark;
- friend class VM_CMS_Final_Remark;
- friend class TraceCMSMemoryManagerStats;
-
- private:
- jlong _time_of_last_gc;
- void update_time_of_last_gc(jlong now) {
- _time_of_last_gc = now;
- }
-
- OopTaskQueueSet* _task_queues;
-
- // Overflow list of grey objects, threaded through mark-word
- // Manipulated with CAS in the parallel/multi-threaded case.
- oopDesc* volatile _overflow_list;
- // The following array-pair keeps track of mark words
- // displaced for accommodating overflow list above.
- // This code will likely be revisited under RFE#4922830.
- Stack<oop, mtGC> _preserved_oop_stack;
- Stack<markWord, mtGC> _preserved_mark_stack;
-
- // In support of multi-threaded concurrent phases
- YieldingFlexibleWorkGang* _conc_workers;
-
- // Performance Counters
- CollectorCounters* _gc_counters;
- CollectorCounters* _cgc_counters;
-
- // Initialization Errors
- bool _completed_initialization;
-
- // In support of ExplicitGCInvokesConcurrent
- static bool _full_gc_requested;
- static GCCause::Cause _full_gc_cause;
- unsigned int _collection_count_start;
-
- // Should we unload classes this concurrent cycle?
- bool _should_unload_classes;
- unsigned int _concurrent_cycles_since_last_unload;
- unsigned int concurrent_cycles_since_last_unload() const {
- return _concurrent_cycles_since_last_unload;
- }
- // Did we (allow) unload classes in the previous concurrent cycle?
- bool unloaded_classes_last_cycle() const {
- return concurrent_cycles_since_last_unload() == 0;
- }
- // Root scanning options for perm gen
- int _roots_scanning_options;
- int roots_scanning_options() const { return _roots_scanning_options; }
- void add_root_scanning_option(int o) { _roots_scanning_options |= o; }
- void remove_root_scanning_option(int o) { _roots_scanning_options &= ~o; }
-
- // Verification support
- CMSBitMap _verification_mark_bm;
- void verify_after_remark_work_1();
- void verify_after_remark_work_2();
-
- // True if any verification flag is on.
- bool _verifying;
- bool verifying() const { return _verifying; }
- void set_verifying(bool v) { _verifying = v; }
-
- void set_did_compact(bool v);
-
- // XXX Move these to CMSStats ??? FIX ME !!!
- elapsedTimer _inter_sweep_timer; // Time between sweeps
- elapsedTimer _intra_sweep_timer; // Time _in_ sweeps
- // Padded decaying average estimates of the above
- AdaptivePaddedAverage _inter_sweep_estimate;
- AdaptivePaddedAverage _intra_sweep_estimate;
-
- CMSTracer* _gc_tracer_cm;
- ConcurrentGCTimer* _gc_timer_cm;
-
- bool _cms_start_registered;
-
- GCHeapSummary _last_heap_summary;
- MetaspaceSummary _last_metaspace_summary;
-
- void register_gc_start(GCCause::Cause cause);
- void register_gc_end();
- void save_heap_summary();
- void report_heap_summary(GCWhen::Type when);
-
- protected:
- ConcurrentMarkSweepGeneration* _cmsGen; // Old gen (CMS)
- MemRegion _span; // Span covering above
- CardTableRS* _ct; // Card table
-
- // CMS marking support structures
- CMSBitMap _markBitMap;
- CMSBitMap _modUnionTable;
- CMSMarkStack _markStack;
-
- HeapWord* _restart_addr; // In support of marking stack overflow
- void lower_restart_addr(HeapWord* low);
-
- // Counters in support of marking stack / work queue overflow handling:
- // a non-zero value indicates certain types of overflow events during
- // the current CMS cycle and could lead to stack resizing efforts at
- // an opportune future time.
- size_t _ser_pmc_preclean_ovflw;
- size_t _ser_pmc_remark_ovflw;
- size_t _par_pmc_remark_ovflw;
- size_t _ser_kac_preclean_ovflw;
- size_t _ser_kac_ovflw;
- size_t _par_kac_ovflw;
- NOT_PRODUCT(ssize_t _num_par_pushes;)
-
- // ("Weak") Reference processing support.
- SpanSubjectToDiscoveryClosure _span_based_discoverer;
- ReferenceProcessor* _ref_processor;
- CMSIsAliveClosure _is_alive_closure;
- // Keep this textually after _markBitMap and _span; c'tor dependency.
-
- ConcurrentMarkSweepThread* _cmsThread; // The thread doing the work
- ModUnionClosurePar _modUnionClosurePar;
-
- // CMS abstract state machine
- // initial_state: Idling
- // next_state(Idling) = {Marking}
- // next_state(Marking) = {Precleaning, Sweeping}
- // next_state(Precleaning) = {AbortablePreclean, FinalMarking}
- // next_state(AbortablePreclean) = {FinalMarking}
- // next_state(FinalMarking) = {Sweeping}
- // next_state(Sweeping) = {Resizing}
- // next_state(Resizing) = {Resetting}
- // next_state(Resetting) = {Idling}
- // The numeric values below are chosen so that:
- // . _collectorState <= Idling == post-sweep && pre-mark
- // . _collectorState in (Idling, Sweeping) == {initial,final}marking ||
- // precleaning || abortablePrecleanb
- public:
- enum CollectorState {
- Resizing = 0,
- Resetting = 1,
- Idling = 2,
- InitialMarking = 3,
- Marking = 4,
- Precleaning = 5,
- AbortablePreclean = 6,
- FinalMarking = 7,
- Sweeping = 8
- };
- protected:
- static CollectorState _collectorState;
-
- // State related to prologue/epilogue invocation for my generations
- bool _between_prologue_and_epilogue;
-
- // Signaling/State related to coordination between fore- and background GC
- // Note: When the baton has been passed from background GC to foreground GC,
- // _foregroundGCIsActive is true and _foregroundGCShouldWait is false.
- static bool _foregroundGCIsActive; // true iff foreground collector is active or
- // wants to go active
- static bool _foregroundGCShouldWait; // true iff background GC is active and has not
- // yet passed the baton to the foreground GC
-
- // Support for CMSScheduleRemark (abortable preclean)
- bool _abort_preclean;
- bool _start_sampling;
-
- int _numYields;
- size_t _numDirtyCards;
- size_t _sweep_count;
-
- // Occupancy used for bootstrapping stats
- double _bootstrap_occupancy;
-
- // Timer
- elapsedTimer _timer;
-
- // Timing, allocation and promotion statistics, used for scheduling.
- CMSStats _stats;
-
- enum CMS_op_type {
- CMS_op_checkpointRootsInitial,
- CMS_op_checkpointRootsFinal
- };
-
- void do_CMS_operation(CMS_op_type op, GCCause::Cause gc_cause);
- bool stop_world_and_do(CMS_op_type op);
-
- OopTaskQueueSet* task_queues() { return _task_queues; }
- YieldingFlexibleWorkGang* conc_workers() { return _conc_workers; }
-
- // Support for parallelizing Eden rescan in CMS remark phase
- void sample_eden(); // ... sample Eden space top
-
- private:
- // Support for parallelizing young gen rescan in CMS remark phase
- ParNewGeneration* _young_gen;
-
- HeapWord* volatile* _top_addr; // ... Top of Eden
- HeapWord** _end_addr; // ... End of Eden
- Mutex* _eden_chunk_lock;
- HeapWord** _eden_chunk_array; // ... Eden partitioning array
- size_t _eden_chunk_index; // ... top (exclusive) of array
- size_t _eden_chunk_capacity; // ... max entries in array
-
- // Support for parallelizing survivor space rescan
- HeapWord** _survivor_chunk_array;
- size_t _survivor_chunk_index;
- size_t _survivor_chunk_capacity;
- size_t* _cursor;
- ChunkArray* _survivor_plab_array;
-
- // Support for marking stack overflow handling
- bool take_from_overflow_list(size_t num, CMSMarkStack* to_stack);
- bool par_take_from_overflow_list(size_t num,
- OopTaskQueue* to_work_q,
- int no_of_gc_threads);
- void push_on_overflow_list(oop p);
- void par_push_on_overflow_list(oop p);
- // The following is, obviously, not, in general, "MT-stable"
- bool overflow_list_is_empty() const;
-
- void preserve_mark_if_necessary(oop p);
- void par_preserve_mark_if_necessary(oop p);
- void preserve_mark_work(oop p, markWord m);
- void restore_preserved_marks_if_any();
- NOT_PRODUCT(bool no_preserved_marks() const;)
- // In support of testing overflow code
- NOT_PRODUCT(int _overflow_counter;)
- NOT_PRODUCT(bool simulate_overflow();) // Sequential
- NOT_PRODUCT(bool par_simulate_overflow();) // MT version
-
- // CMS work methods
- void checkpointRootsInitialWork(); // Initial checkpoint work
-
- // A return value of false indicates failure due to stack overflow
- bool markFromRootsWork(); // Concurrent marking work
-
- public: // FIX ME!!! only for testing
- bool do_marking_st(); // Single-threaded marking
- bool do_marking_mt(); // Multi-threaded marking
-
- private:
-
- // Concurrent precleaning work
- size_t preclean_mod_union_table(ConcurrentMarkSweepGeneration* old_gen,
- ScanMarkedObjectsAgainCarefullyClosure* cl);
- size_t preclean_card_table(ConcurrentMarkSweepGeneration* old_gen,
- ScanMarkedObjectsAgainCarefullyClosure* cl);
- // Does precleaning work, returning a quantity indicative of
- // the amount of "useful work" done.
- size_t preclean_work(bool clean_refs, bool clean_survivors);
- void preclean_cld(MarkRefsIntoAndScanClosure* cl, Mutex* freelistLock);
- void abortable_preclean(); // Preclean while looking for possible abort
- void initialize_sequential_subtasks_for_young_gen_rescan(int i);
- // Helper function for above; merge-sorts the per-thread plab samples
- void merge_survivor_plab_arrays(ContiguousSpace* surv, int no_of_gc_threads);
- // Resets (i.e. clears) the per-thread plab sample vectors
- void reset_survivor_plab_arrays();
-
- // Final (second) checkpoint work
- void checkpointRootsFinalWork();
- // Work routine for parallel version of remark
- void do_remark_parallel();
- // Work routine for non-parallel version of remark
- void do_remark_non_parallel();
- // Reference processing work routine (during second checkpoint)
- void refProcessingWork();
-
- // Concurrent sweeping work
- void sweepWork(ConcurrentMarkSweepGeneration* old_gen);
-
- // Concurrent resetting of support data structures
- void reset_concurrent();
- // Resetting of support data structures from a STW full GC
- void reset_stw();
-
- // Clear _expansion_cause fields of constituent generations
- void clear_expansion_cause();
-
- // An auxiliary method used to record the ends of
- // used regions of each generation to limit the extent of sweep
- void save_sweep_limits();
-
- // A work method used by the foreground collector to do
- // a mark-sweep-compact.
- void do_compaction_work(bool clear_all_soft_refs);
-
- // Work methods for reporting concurrent mode interruption or failure
- bool is_external_interruption();
- void report_concurrent_mode_interruption();
-
- // If the background GC is active, acquire control from the background
- // GC and do the collection.
- void acquire_control_and_collect(bool full, bool clear_all_soft_refs);
-
- // For synchronizing passing of control from background to foreground
- // GC. waitForForegroundGC() is called by the background
- // collector. It if had to wait for a foreground collection,
- // it returns true and the background collection should assume
- // that the collection was finished by the foreground
- // collector.
- bool waitForForegroundGC();
-
- size_t block_size_using_printezis_bits(HeapWord* addr) const;
- size_t block_size_if_printezis_bits(HeapWord* addr) const;
- HeapWord* next_card_start_after_block(HeapWord* addr) const;
-
- void setup_cms_unloading_and_verification_state();
- public:
- CMSCollector(ConcurrentMarkSweepGeneration* cmsGen,
- CardTableRS* ct);
- ConcurrentMarkSweepThread* cmsThread() { return _cmsThread; }
-
- MemRegion ref_processor_span() const { return _span_based_discoverer.span(); }
- ReferenceProcessor* ref_processor() { return _ref_processor; }
- void ref_processor_init();
-
- Mutex* bitMapLock() const { return _markBitMap.lock(); }
- static CollectorState abstract_state() { return _collectorState; }
-
- bool should_abort_preclean() const; // Whether preclean should be aborted.
- size_t get_eden_used() const;
- size_t get_eden_capacity() const;
-
- ConcurrentMarkSweepGeneration* cmsGen() { return _cmsGen; }
-
- // Locking checks
- NOT_PRODUCT(static bool have_cms_token();)
-
- bool shouldConcurrentCollect();
-
- void collect(bool full,
- bool clear_all_soft_refs,
- size_t size,
- bool tlab);
- void collect_in_background(GCCause::Cause cause);
-
- // In support of ExplicitGCInvokesConcurrent
- static void request_full_gc(unsigned int full_gc_count, GCCause::Cause cause);
- // Should we unload classes in a particular concurrent cycle?
- bool should_unload_classes() const {
- return _should_unload_classes;
- }
- void update_should_unload_classes();
-
- void direct_allocated(HeapWord* start, size_t size);
-
- // Object is dead if not marked and current phase is sweeping.
- bool is_dead_obj(oop obj) const;
-
- // After a promotion (of "start"), do any necessary marking.
- // If "par", then it's being done by a parallel GC thread.
- // The last two args indicate if we need precise marking
- // and if so the size of the object so it can be dirtied
- // in its entirety.
- void promoted(bool par, HeapWord* start,
- bool is_obj_array, size_t obj_size);
-
- void getFreelistLocks() const;
- void releaseFreelistLocks() const;
- bool haveFreelistLocks() const;
-
- // Adjust size of underlying generation
- void compute_new_size();
-
- // GC prologue and epilogue
- void gc_prologue(bool full);
- void gc_epilogue(bool full);
-
- jlong time_of_last_gc(jlong now) {
- if (_collectorState <= Idling) {
- // gc not in progress
- return _time_of_last_gc;
- } else {
- // collection in progress
- return now;
- }
- }
-
- // Support for parallel remark of survivor space
- void* get_data_recorder(int thr_num);
- void sample_eden_chunk();
-
- CMSBitMap* markBitMap() { return &_markBitMap; }
- void directAllocated(HeapWord* start, size_t size);
-
- // Main CMS steps and related support
- void checkpointRootsInitial();
- bool markFromRoots(); // a return value of false indicates failure
- // due to stack overflow
- void preclean();
- void checkpointRootsFinal();
- void sweep();
-
- // Check that the currently executing thread is the expected
- // one (foreground collector or background collector).
- static void check_correct_thread_executing() PRODUCT_RETURN;
-
- NOT_PRODUCT(bool is_cms_reachable(HeapWord* addr);)
-
- // Performance Counter Support
- CollectorCounters* counters() { return _gc_counters; }
- CollectorCounters* cgc_counters() { return _cgc_counters; }
-
- // Timer stuff
- void startTimer() { assert(!_timer.is_active(), "Error"); _timer.start(); }
- void stopTimer() { assert( _timer.is_active(), "Error"); _timer.stop(); }
- void resetTimer() { assert(!_timer.is_active(), "Error"); _timer.reset(); }
- jlong timerTicks() { assert(!_timer.is_active(), "Error"); return _timer.ticks(); }
-
- int yields() { return _numYields; }
- void resetYields() { _numYields = 0; }
- void incrementYields() { _numYields++; }
- void resetNumDirtyCards() { _numDirtyCards = 0; }
- void incrementNumDirtyCards(size_t num) { _numDirtyCards += num; }
- size_t numDirtyCards() { return _numDirtyCards; }
-
- static bool foregroundGCShouldWait() { return _foregroundGCShouldWait; }
- static void set_foregroundGCShouldWait(bool v) { _foregroundGCShouldWait = v; }
- static bool foregroundGCIsActive() { return _foregroundGCIsActive; }
- static void set_foregroundGCIsActive(bool v) { _foregroundGCIsActive = v; }
- size_t sweep_count() const { return _sweep_count; }
- void increment_sweep_count() { _sweep_count++; }
-
- // Timers/stats for gc scheduling and incremental mode pacing.
- CMSStats& stats() { return _stats; }
-
- // Adaptive size policy
- AdaptiveSizePolicy* size_policy();
-
- static void print_on_error(outputStream* st);
-
- // Debugging
- void verify();
- bool verify_after_remark();
- void verify_ok_to_terminate() const PRODUCT_RETURN;
- void verify_work_stacks_empty() const PRODUCT_RETURN;
- void verify_overflow_empty() const PRODUCT_RETURN;
-
- // Convenience methods in support of debugging
- static const size_t skip_header_HeapWords() PRODUCT_RETURN0;
- HeapWord* block_start(const void* p) const PRODUCT_RETURN0;
-
- // Accessors
- CMSMarkStack* verification_mark_stack() { return &_markStack; }
- CMSBitMap* verification_mark_bm() { return &_verification_mark_bm; }
-
- // Initialization errors
- bool completed_initialization() { return _completed_initialization; }
-
- void print_eden_and_survivor_chunk_arrays();
-
- ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
-};
-
-class CMSExpansionCause : public AllStatic {
- public:
- enum Cause {
- _no_expansion,
- _satisfy_free_ratio,
- _satisfy_promotion,
- _satisfy_allocation,
- _allocate_par_lab,
- _allocate_par_spooling_space,
- _adaptive_size_policy
- };
- // Return a string describing the cause of the expansion.
- static const char* to_string(CMSExpansionCause::Cause cause);
-};
-
-class ConcurrentMarkSweepGeneration: public CardGeneration {
- friend class VMStructs;
- friend class ConcurrentMarkSweepThread;
- friend class ConcurrentMarkSweep;
- friend class CMSCollector;
- protected:
- static CMSCollector* _collector; // the collector that collects us
- CompactibleFreeListSpace* _cmsSpace; // underlying space (only one for now)
-
- // Performance Counters
- GenerationCounters* _gen_counters;
- GSpaceCounters* _space_counters;
-
- // Words directly allocated, used by CMSStats.
- size_t _direct_allocated_words;
-
- // Non-product stat counters
- NOT_PRODUCT(
- size_t _numObjectsPromoted;
- size_t _numWordsPromoted;
- size_t _numObjectsAllocated;
- size_t _numWordsAllocated;
- )
-
- // Used for sizing decisions
- bool _incremental_collection_failed;
- bool incremental_collection_failed() {
- return _incremental_collection_failed;
- }
- void set_incremental_collection_failed() {
- _incremental_collection_failed = true;
- }
- void clear_incremental_collection_failed() {
- _incremental_collection_failed = false;
- }
-
- // accessors
- void set_expansion_cause(CMSExpansionCause::Cause v) { _expansion_cause = v;}
- CMSExpansionCause::Cause expansion_cause() const { return _expansion_cause; }
-
- // Accessing spaces
- CompactibleSpace* space() const { return (CompactibleSpace*)_cmsSpace; }
-
- private:
- // For parallel young-gen GC support.
- CMSParGCThreadState** _par_gc_thread_states;
-
- // Reason generation was expanded
- CMSExpansionCause::Cause _expansion_cause;
-
- // In support of MinChunkSize being larger than min object size
- const double _dilatation_factor;
-
- // True if a compacting collection was done.
- bool _did_compact;
- bool did_compact() { return _did_compact; }
-
- // Fraction of current occupancy at which to start a CMS collection which
- // will collect this generation (at least).
- double _initiating_occupancy;
-
- protected:
- // Shrink generation by specified size (returns false if unable to shrink)
- void shrink_free_list_by(size_t bytes);
-
- // Update statistics for GC
- virtual void update_gc_stats(Generation* current_generation, bool full);
-
- // Maximum available space in the generation (including uncommitted)
- // space.
- size_t max_available() const;
-
- // getter and initializer for _initiating_occupancy field.
- double initiating_occupancy() const { return _initiating_occupancy; }
- void init_initiating_occupancy(intx io, uintx tr);
-
- void expand_for_gc_cause(size_t bytes, size_t expand_bytes, CMSExpansionCause::Cause cause);
-
- void assert_correct_size_change_locking();
-
- public:
- ConcurrentMarkSweepGeneration(ReservedSpace rs,
- size_t initial_byte_size,
- size_t min_byte_size,
- size_t max_byte_size,
- CardTableRS* ct);
-
- // Accessors
- CMSCollector* collector() const { return _collector; }
- static void set_collector(CMSCollector* collector) {
- assert(_collector == NULL, "already set");
- _collector = collector;
- }
- CompactibleFreeListSpace* cmsSpace() const { return _cmsSpace; }
-
- Mutex* freelistLock() const;
-
- virtual Generation::Name kind() { return Generation::ConcurrentMarkSweep; }
-
- void set_did_compact(bool v) { _did_compact = v; }
-
- bool refs_discovery_is_atomic() const { return false; }
- bool refs_discovery_is_mt() const {
- // Note: CMS does MT-discovery during the parallel-remark
- // phases. Use ReferenceProcessorMTMutator to make refs
- // discovery MT-safe during such phases or other parallel
- // discovery phases in the future. This may all go away
- // if/when we decide that refs discovery is sufficiently
- // rare that the cost of the CAS's involved is in the
- // noise. That's a measurement that should be done, and
- // the code simplified if that turns out to be the case.
- return ConcGCThreads > 1;
- }
-
- // Override
- virtual void ref_processor_init();
-
- void clear_expansion_cause() { _expansion_cause = CMSExpansionCause::_no_expansion; }
-
- // Space enquiries
- double occupancy() const { return ((double)used())/((double)capacity()); }
- size_t contiguous_available() const;
- size_t unsafe_max_alloc_nogc() const;
- size_t used_stable() const;
-
- // over-rides
- MemRegion used_region_at_save_marks() const;
-
- // Adjust quantities in the generation affected by
- // the compaction.
- void reset_after_compaction();
-
- // Allocation support
- HeapWord* allocate(size_t size, bool tlab);
- HeapWord* have_lock_and_allocate(size_t size, bool tlab);
- oop promote(oop obj, size_t obj_size);
- HeapWord* par_allocate(size_t size, bool tlab) {
- return allocate(size, tlab);
- }
-
-
- // Used by CMSStats to track direct allocation. The value is sampled and
- // reset after each young gen collection.
- size_t direct_allocated_words() const { return _direct_allocated_words; }
- void reset_direct_allocated_words() { _direct_allocated_words = 0; }
-
- // Overrides for parallel promotion.
- virtual oop par_promote(int thread_num,
- oop obj, markWord m, size_t word_sz);
- virtual void par_promote_alloc_done(int thread_num);
- virtual void par_oop_since_save_marks_iterate_done(int thread_num);
-
- virtual bool promotion_attempt_is_safe(size_t promotion_in_bytes) const;
-
- // Inform this (old) generation that a promotion failure was
- // encountered during a collection of the young generation.
- virtual void promotion_failure_occurred();
-
- bool should_collect(bool full, size_t size, bool tlab);
- virtual bool should_concurrent_collect() const;
- virtual bool is_too_full() const;
- void collect(bool full,
- bool clear_all_soft_refs,
- size_t size,
- bool tlab);
-
- HeapWord* expand_and_allocate(size_t word_size,
- bool tlab,
- bool parallel = false);
-
- // GC prologue and epilogue
- void gc_prologue(bool full);
- void gc_prologue_work(bool full, bool registerClosure,
- ModUnionClosure* modUnionClosure);
- void gc_epilogue(bool full);
- void gc_epilogue_work(bool full);
-
- // Time since last GC of this generation
- jlong time_of_last_gc(jlong now) {
- return collector()->time_of_last_gc(now);
- }
- void update_time_of_last_gc(jlong now) {
- collector()-> update_time_of_last_gc(now);
- }
-
- // Allocation failure
- void shrink(size_t bytes);
- HeapWord* expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz);
- bool expand_and_ensure_spooling_space(PromotionInfo* promo);
-
- // Iteration support and related enquiries
- void save_marks();
- bool no_allocs_since_save_marks();
-
- // Iteration support specific to CMS generations
- void save_sweep_limit();
-
- // More iteration support
- virtual void oop_iterate(OopIterateClosure* cl);
- virtual void safe_object_iterate(ObjectClosure* cl);
- virtual void object_iterate(ObjectClosure* cl);
-
- template <typename OopClosureType>
- void oop_since_save_marks_iterate(OopClosureType* cl);
-
- // Smart allocation XXX -- move to CFLSpace?
- void setNearLargestChunk();
- bool isNearLargestChunk(HeapWord* addr);
-
- // Get the chunk at the end of the space. Delegates to
- // the space.
- FreeChunk* find_chunk_at_end();
-
- void post_compact();
-
- // Debugging
- void prepare_for_verify();
- void verify();
- void print_statistics() PRODUCT_RETURN;
-
- // Performance Counters support
- virtual void update_counters();
- virtual void update_counters(size_t used);
- void initialize_performance_counters(size_t min_old_size, size_t max_old_size);
- CollectorCounters* counters() { return collector()->counters(); }
-
- // Support for parallel remark of survivor space
- void* get_data_recorder(int thr_num) {
- //Delegate to collector
- return collector()->get_data_recorder(thr_num);
- }
- void sample_eden_chunk() {
- //Delegate to collector
- return collector()->sample_eden_chunk();
- }
-
- // Printing
- const char* name() const;
- virtual const char* short_name() const { return "CMS"; }
- void print() const;
-
- // Resize the generation after a compacting GC. The
- // generation can be treated as a contiguous space
- // after the compaction.
- virtual void compute_new_size();
- // Resize the generation after a non-compacting
- // collection.
- void compute_new_size_free_list();
-};
-
-//
-// Closures of various sorts used by CMS to accomplish its work
-//
-
-// This closure is used to do concurrent marking from the roots
-// following the first checkpoint.
-class MarkFromRootsClosure: public BitMapClosure {
- CMSCollector* _collector;
- MemRegion _span;
- CMSBitMap* _bitMap;
- CMSBitMap* _mut;
- CMSMarkStack* _markStack;
- bool _yield;
- int _skipBits;
- HeapWord* _finger;
- HeapWord* _threshold;
- DEBUG_ONLY(bool _verifying;)
-
- public:
- MarkFromRootsClosure(CMSCollector* collector, MemRegion span,
- CMSBitMap* bitMap,
- CMSMarkStack* markStack,
- bool should_yield, bool verifying = false);
- bool do_bit(size_t offset);
- void reset(HeapWord* addr);
- inline void do_yield_check();
-
- private:
- void scanOopsInOop(HeapWord* ptr);
- void do_yield_work();
-};
-
-// This closure is used to do concurrent multi-threaded
-// marking from the roots following the first checkpoint.
-// XXX This should really be a subclass of The serial version
-// above, but i have not had the time to refactor things cleanly.
-class ParMarkFromRootsClosure: public BitMapClosure {
- CMSCollector* _collector;
- MemRegion _whole_span;
- MemRegion _span;
- CMSBitMap* _bit_map;
- CMSBitMap* _mut;
- OopTaskQueue* _work_queue;
- CMSMarkStack* _overflow_stack;
- int _skip_bits;
- HeapWord* _finger;
- HeapWord* _threshold;
- CMSConcMarkingTask* _task;
- public:
- ParMarkFromRootsClosure(CMSConcMarkingTask* task, CMSCollector* collector,
- MemRegion span,
- CMSBitMap* bit_map,
- OopTaskQueue* work_queue,
- CMSMarkStack* overflow_stack);
- bool do_bit(size_t offset);
- inline void do_yield_check();
-
- private:
- void scan_oops_in_oop(HeapWord* ptr);
- void do_yield_work();
- bool get_work_from_overflow_stack();
-};
-
-// The following closures are used to do certain kinds of verification of
-// CMS marking.
-class PushAndMarkVerifyClosure: public MetadataVisitingOopIterateClosure {
- CMSCollector* _collector;
- MemRegion _span;
- CMSBitMap* _verification_bm;
- CMSBitMap* _cms_bm;
- CMSMarkStack* _mark_stack;
- protected:
- void do_oop(oop p);
- template <class T> void do_oop_work(T *p);
-
- public:
- PushAndMarkVerifyClosure(CMSCollector* cms_collector,
- MemRegion span,
- CMSBitMap* verification_bm,
- CMSBitMap* cms_bm,
- CMSMarkStack* mark_stack);
- void do_oop(oop* p);
- void do_oop(narrowOop* p);
-
- // Deal with a stack overflow condition
- void handle_stack_overflow(HeapWord* lost);
-};
-
-class MarkFromRootsVerifyClosure: public BitMapClosure {
- CMSCollector* _collector;
- MemRegion _span;
- CMSBitMap* _verification_bm;
- CMSBitMap* _cms_bm;
- CMSMarkStack* _mark_stack;
- HeapWord* _finger;
- PushAndMarkVerifyClosure _pam_verify_closure;
- public:
- MarkFromRootsVerifyClosure(CMSCollector* collector, MemRegion span,
- CMSBitMap* verification_bm,
- CMSBitMap* cms_bm,
- CMSMarkStack* mark_stack);
- bool do_bit(size_t offset);
- void reset(HeapWord* addr);
-};
-
-
-// This closure is used to check that a certain set of bits is
-// "empty" (i.e. the bit vector doesn't have any 1-bits).
-class FalseBitMapClosure: public BitMapClosure {
- public:
- bool do_bit(size_t offset) {
- guarantee(false, "Should not have a 1 bit");
- return true;
- }
-};
-
-// A version of ObjectClosure with "memory" (see _previous_address below)
-class UpwardsObjectClosure: public BoolObjectClosure {
- HeapWord* _previous_address;
- public:
- UpwardsObjectClosure() : _previous_address(NULL) { }
- void set_previous(HeapWord* addr) { _previous_address = addr; }
- HeapWord* previous() { return _previous_address; }
- // A return value of "true" can be used by the caller to decide
- // if this object's end should *NOT* be recorded in
- // _previous_address above.
- virtual bool do_object_bm(oop obj, MemRegion mr) = 0;
-};
-
-// This closure is used during the second checkpointing phase
-// to rescan the marked objects on the dirty cards in the mod
-// union table and the card table proper. It's invoked via
-// MarkFromDirtyCardsClosure below. It uses either
-// [Par_]MarkRefsIntoAndScanClosure (Par_ in the parallel case)
-// declared in genOopClosures.hpp to accomplish some of its work.
-// In the parallel case the bitMap is shared, so access to
-// it needs to be suitably synchronized for updates by embedded
-// closures that update it; however, this closure itself only
-// reads the bit_map and because it is idempotent, is immune to
-// reading stale values.
-class ScanMarkedObjectsAgainClosure: public UpwardsObjectClosure {
- #ifdef ASSERT
- CMSCollector* _collector;
- MemRegion _span;
- union {
- CMSMarkStack* _mark_stack;
- OopTaskQueue* _work_queue;
- };
- #endif // ASSERT
- bool _parallel;
- CMSBitMap* _bit_map;
- union {
- MarkRefsIntoAndScanClosure* _scan_closure;
- ParMarkRefsIntoAndScanClosure* _par_scan_closure;
- };
-
- public:
- ScanMarkedObjectsAgainClosure(CMSCollector* collector,
- MemRegion span,
- ReferenceProcessor* rp,
- CMSBitMap* bit_map,
- CMSMarkStack* mark_stack,
- MarkRefsIntoAndScanClosure* cl):
- #ifdef ASSERT
- _collector(collector),
- _span(span),
- _mark_stack(mark_stack),
- #endif // ASSERT
- _parallel(false),
- _bit_map(bit_map),
- _scan_closure(cl) { }
-
- ScanMarkedObjectsAgainClosure(CMSCollector* collector,
- MemRegion span,
- ReferenceProcessor* rp,
- CMSBitMap* bit_map,
- OopTaskQueue* work_queue,
- ParMarkRefsIntoAndScanClosure* cl):
- #ifdef ASSERT
- _collector(collector),
- _span(span),
- _work_queue(work_queue),
- #endif // ASSERT
- _parallel(true),
- _bit_map(bit_map),
- _par_scan_closure(cl) { }
-
- bool do_object_b(oop obj) {
- guarantee(false, "Call do_object_b(oop, MemRegion) form instead");
- return false;
- }
- bool do_object_bm(oop p, MemRegion mr);
-};
-
-// This closure is used during the second checkpointing phase
-// to rescan the marked objects on the dirty cards in the mod
-// union table and the card table proper. It invokes
-// ScanMarkedObjectsAgainClosure above to accomplish much of its work.
-// In the parallel case, the bit map is shared and requires
-// synchronized access.
-class MarkFromDirtyCardsClosure: public MemRegionClosure {
- CompactibleFreeListSpace* _space;
- ScanMarkedObjectsAgainClosure _scan_cl;
- size_t _num_dirty_cards;
-
- public:
- MarkFromDirtyCardsClosure(CMSCollector* collector,
- MemRegion span,
- CompactibleFreeListSpace* space,
- CMSBitMap* bit_map,
- CMSMarkStack* mark_stack,
- MarkRefsIntoAndScanClosure* cl):
- _space(space),
- _scan_cl(collector, span, collector->ref_processor(), bit_map,
- mark_stack, cl),
- _num_dirty_cards(0) { }
-
- MarkFromDirtyCardsClosure(CMSCollector* collector,
- MemRegion span,
- CompactibleFreeListSpace* space,
- CMSBitMap* bit_map,
- OopTaskQueue* work_queue,
- ParMarkRefsIntoAndScanClosure* cl):
- _space(space),
- _scan_cl(collector, span, collector->ref_processor(), bit_map,
- work_queue, cl),
- _num_dirty_cards(0) { }
-
- void do_MemRegion(MemRegion mr);
- void set_space(CompactibleFreeListSpace* space) { _space = space; }
- size_t num_dirty_cards() { return _num_dirty_cards; }
-};
-
-// This closure is used in the non-product build to check
-// that there are no MemRegions with a certain property.
-class FalseMemRegionClosure: public MemRegionClosure {
- void do_MemRegion(MemRegion mr) {
- guarantee(!mr.is_empty(), "Shouldn't be empty");
- guarantee(false, "Should never be here");
- }
-};
-
-// This closure is used during the precleaning phase
-// to "carefully" rescan marked objects on dirty cards.
-// It uses MarkRefsIntoAndScanClosure declared in genOopClosures.hpp
-// to accomplish some of its work.
-class ScanMarkedObjectsAgainCarefullyClosure: public ObjectClosureCareful {
- CMSCollector* _collector;
- MemRegion _span;
- bool _yield;
- Mutex* _freelistLock;
- CMSBitMap* _bitMap;
- CMSMarkStack* _markStack;
- MarkRefsIntoAndScanClosure* _scanningClosure;
- DEBUG_ONLY(HeapWord* _last_scanned_object;)
-
- public:
- ScanMarkedObjectsAgainCarefullyClosure(CMSCollector* collector,
- MemRegion span,
- CMSBitMap* bitMap,
- CMSMarkStack* markStack,
- MarkRefsIntoAndScanClosure* cl,
- bool should_yield):
- _collector(collector),
- _span(span),
- _yield(should_yield),
- _bitMap(bitMap),
- _markStack(markStack),
- _scanningClosure(cl)
- DEBUG_ONLY(COMMA _last_scanned_object(NULL))
- { }
-
- void do_object(oop p) {
- guarantee(false, "call do_object_careful instead");
- }
-
- size_t do_object_careful(oop p) {
- guarantee(false, "Unexpected caller");
- return 0;
- }
-
- size_t do_object_careful_m(oop p, MemRegion mr);
-
- void setFreelistLock(Mutex* m) {
- _freelistLock = m;
- _scanningClosure->set_freelistLock(m);
- }
-
- private:
- inline bool do_yield_check();
-
- void do_yield_work();
-};
-
-class SurvivorSpacePrecleanClosure: public ObjectClosureCareful {
- CMSCollector* _collector;
- MemRegion _span;
- bool _yield;
- CMSBitMap* _bit_map;
- CMSMarkStack* _mark_stack;
- PushAndMarkClosure* _scanning_closure;
- unsigned int _before_count;
-
- public:
- SurvivorSpacePrecleanClosure(CMSCollector* collector,
- MemRegion span,
- CMSBitMap* bit_map,
- CMSMarkStack* mark_stack,
- PushAndMarkClosure* cl,
- unsigned int before_count,
- bool should_yield):
- _collector(collector),
- _span(span),
- _yield(should_yield),
- _bit_map(bit_map),
- _mark_stack(mark_stack),
- _scanning_closure(cl),
- _before_count(before_count)
- { }
-
- void do_object(oop p) {
- guarantee(false, "call do_object_careful instead");
- }
-
- size_t do_object_careful(oop p);
-
- size_t do_object_careful_m(oop p, MemRegion mr) {
- guarantee(false, "Unexpected caller");
- return 0;
- }
-
- private:
- inline void do_yield_check();
- void do_yield_work();
-};
-
-// This closure is used to accomplish the sweeping work
-// after the second checkpoint but before the concurrent reset
-// phase.
-//
-// Terminology
-// left hand chunk (LHC) - block of one or more chunks currently being
-// coalesced. The LHC is available for coalescing with a new chunk.
-// right hand chunk (RHC) - block that is currently being swept that is
-// free or garbage that can be coalesced with the LHC.
-// _inFreeRange is true if there is currently a LHC
-// _lastFreeRangeCoalesced is true if the LHC consists of more than one chunk.
-// _freeRangeInFreeLists is true if the LHC is in the free lists.
-// _freeFinger is the address of the current LHC
-class SweepClosure: public BlkClosureCareful {
- CMSCollector* _collector; // collector doing the work
- ConcurrentMarkSweepGeneration* _g; // Generation being swept
- CompactibleFreeListSpace* _sp; // Space being swept
- HeapWord* _limit;// the address at or above which the sweep should stop
- // because we do not expect newly garbage blocks
- // eligible for sweeping past that address.
- Mutex* _freelistLock; // Free list lock (in space)
- CMSBitMap* _bitMap; // Marking bit map (in
- // generation)
- bool _inFreeRange; // Indicates if we are in the
- // midst of a free run
- bool _freeRangeInFreeLists;
- // Often, we have just found
- // a free chunk and started
- // a new free range; we do not
- // eagerly remove this chunk from
- // the free lists unless there is
- // a possibility of coalescing.
- // When true, this flag indicates
- // that the _freeFinger below
- // points to a potentially free chunk
- // that may still be in the free lists
- bool _lastFreeRangeCoalesced;
- // free range contains chunks
- // coalesced
- bool _yield;
- // Whether sweeping should be
- // done with yields. For instance
- // when done by the foreground
- // collector we shouldn't yield.
- HeapWord* _freeFinger; // When _inFreeRange is set, the
- // pointer to the "left hand
- // chunk"
- size_t _freeRangeSize;
- // When _inFreeRange is set, this
- // indicates the accumulated size
- // of the "left hand chunk"
- NOT_PRODUCT(
- size_t _numObjectsFreed;
- size_t _numWordsFreed;
- size_t _numObjectsLive;
- size_t _numWordsLive;
- size_t _numObjectsAlreadyFree;
- size_t _numWordsAlreadyFree;
- FreeChunk* _last_fc;
- )
- private:
- // Code that is common to a free chunk or garbage when
- // encountered during sweeping.
- void do_post_free_or_garbage_chunk(FreeChunk *fc, size_t chunkSize);
- // Process a free chunk during sweeping.
- void do_already_free_chunk(FreeChunk *fc);
- // Work method called when processing an already free or a
- // freshly garbage chunk to do a lookahead and possibly a
- // preemptive flush if crossing over _limit.
- void lookahead_and_flush(FreeChunk* fc, size_t chunkSize);
- // Process a garbage chunk during sweeping.
- size_t do_garbage_chunk(FreeChunk *fc);
- // Process a live chunk during sweeping.
- size_t do_live_chunk(FreeChunk* fc);
-
- // Accessors.
- HeapWord* freeFinger() const { return _freeFinger; }
- void set_freeFinger(HeapWord* v) { _freeFinger = v; }
- bool inFreeRange() const { return _inFreeRange; }
- void set_inFreeRange(bool v) { _inFreeRange = v; }
- bool lastFreeRangeCoalesced() const { return _lastFreeRangeCoalesced; }
- void set_lastFreeRangeCoalesced(bool v) { _lastFreeRangeCoalesced = v; }
- bool freeRangeInFreeLists() const { return _freeRangeInFreeLists; }
- void set_freeRangeInFreeLists(bool v) { _freeRangeInFreeLists = v; }
-
- // Initialize a free range.
- void initialize_free_range(HeapWord* freeFinger, bool freeRangeInFreeLists);
- // Return this chunk to the free lists.
- void flush_cur_free_chunk(HeapWord* chunk, size_t size);
-
- // Check if we should yield and do so when necessary.
- inline void do_yield_check(HeapWord* addr);
-
- // Yield
- void do_yield_work(HeapWord* addr);
-
- // Debugging/Printing
- void print_free_block_coalesced(FreeChunk* fc) const;
-
- public:
- SweepClosure(CMSCollector* collector, ConcurrentMarkSweepGeneration* g,
- CMSBitMap* bitMap, bool should_yield);
- ~SweepClosure() PRODUCT_RETURN;
-
- size_t do_blk_careful(HeapWord* addr);
- void print() const { print_on(tty); }
- void print_on(outputStream *st) const;
-};
-
-// Closures related to weak references processing
-
-// During CMS' weak reference processing, this is a
-// work-routine/closure used to complete transitive
-// marking of objects as live after a certain point
-// in which an initial set has been completely accumulated.
-// This closure is currently used both during the final
-// remark stop-world phase, as well as during the concurrent
-// precleaning of the discovered reference lists.
-class CMSDrainMarkingStackClosure: public VoidClosure {
- CMSCollector* _collector;
- MemRegion _span;
- CMSMarkStack* _mark_stack;
- CMSBitMap* _bit_map;
- CMSKeepAliveClosure* _keep_alive;
- bool _concurrent_precleaning;
- public:
- CMSDrainMarkingStackClosure(CMSCollector* collector, MemRegion span,
- CMSBitMap* bit_map, CMSMarkStack* mark_stack,
- CMSKeepAliveClosure* keep_alive,
- bool cpc):
- _collector(collector),
- _span(span),
- _mark_stack(mark_stack),
- _bit_map(bit_map),
- _keep_alive(keep_alive),
- _concurrent_precleaning(cpc) {
- assert(_concurrent_precleaning == _keep_alive->concurrent_precleaning(),
- "Mismatch");
- }
-
- void do_void();
-};
-
-// A parallel version of CMSDrainMarkingStackClosure above.
-class CMSParDrainMarkingStackClosure: public VoidClosure {
- CMSCollector* _collector;
- MemRegion _span;
- OopTaskQueue* _work_queue;
- CMSBitMap* _bit_map;
- CMSInnerParMarkAndPushClosure _mark_and_push;
-
- public:
- CMSParDrainMarkingStackClosure(CMSCollector* collector,
- MemRegion span, CMSBitMap* bit_map,
- OopTaskQueue* work_queue):
- _collector(collector),
- _span(span),
- _work_queue(work_queue),
- _bit_map(bit_map),
- _mark_and_push(collector, span, bit_map, work_queue) { }
-
- public:
- void trim_queue(uint max);
- void do_void();
-};
-
-// Allow yielding or short-circuiting of reference list
-// precleaning work.
-class CMSPrecleanRefsYieldClosure: public YieldClosure {
- CMSCollector* _collector;
- void do_yield_work();
- public:
- CMSPrecleanRefsYieldClosure(CMSCollector* collector):
- _collector(collector) {}
- virtual bool should_return();
-};
-
-
-// Convenience class that locks free list locks for given CMS collector
-class FreelistLocker: public StackObj {
- private:
- CMSCollector* _collector;
- public:
- FreelistLocker(CMSCollector* collector):
- _collector(collector) {
- _collector->getFreelistLocks();
- }
-
- ~FreelistLocker() {
- _collector->releaseFreelistLocks();
- }
-};
-
-// Mark all dead objects in a given space.
-class MarkDeadObjectsClosure: public BlkClosure {
- const CMSCollector* _collector;
- const CompactibleFreeListSpace* _sp;
- CMSBitMap* _live_bit_map;
- CMSBitMap* _dead_bit_map;
-public:
- MarkDeadObjectsClosure(const CMSCollector* collector,
- const CompactibleFreeListSpace* sp,
- CMSBitMap *live_bit_map,
- CMSBitMap *dead_bit_map) :
- _collector(collector),
- _sp(sp),
- _live_bit_map(live_bit_map),
- _dead_bit_map(dead_bit_map) {}
- size_t do_blk(HeapWord* addr);
-};
-
-class TraceCMSMemoryManagerStats : public TraceMemoryManagerStats {
-
- public:
- TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause);
-};
-
-
-#endif // SHARE_GC_CMS_CONCURRENTMARKSWEEPGENERATION_HPP