diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/hotspot/share/gc/g1/g1ConcurrentMark.hpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/hotspot/share/gc/g1/g1ConcurrentMark.hpp Tue Sep 12 19:03:39 2017 +0200 @@ -0,0 +1,915 @@ +/* + * Copyright (c) 2001, 2017, 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_VM_GC_G1_G1CONCURRENTMARK_HPP +#define SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP + +#include "classfile/javaClasses.hpp" +#include "gc/g1/g1ConcurrentMarkBitMap.hpp" +#include "gc/g1/g1ConcurrentMarkObjArrayProcessor.hpp" +#include "gc/g1/g1RegionToSpaceMapper.hpp" +#include "gc/g1/heapRegionSet.hpp" +#include "gc/shared/taskqueue.hpp" + +class G1CollectedHeap; +class G1CMTask; +class G1ConcurrentMark; +class ConcurrentGCTimer; +class G1OldTracer; +class G1SurvivorRegions; + +#ifdef _MSC_VER +#pragma warning(push) +// warning C4522: multiple assignment operators specified +#pragma warning(disable:4522) +#endif + +// This is a container class for either an oop or a continuation address for +// mark stack entries. Both are pushed onto the mark stack. +class G1TaskQueueEntry VALUE_OBJ_CLASS_SPEC { +private: + void* _holder; + + static const uintptr_t ArraySliceBit = 1; + + G1TaskQueueEntry(oop obj) : _holder(obj) { + assert(_holder != NULL, "Not allowed to set NULL task queue element"); + } + G1TaskQueueEntry(HeapWord* addr) : _holder((void*)((uintptr_t)addr | ArraySliceBit)) { } +public: + G1TaskQueueEntry(const G1TaskQueueEntry& other) { _holder = other._holder; } + G1TaskQueueEntry() : _holder(NULL) { } + + static G1TaskQueueEntry from_slice(HeapWord* what) { return G1TaskQueueEntry(what); } + static G1TaskQueueEntry from_oop(oop obj) { return G1TaskQueueEntry(obj); } + + G1TaskQueueEntry& operator=(const G1TaskQueueEntry& t) { + _holder = t._holder; + return *this; + } + + volatile G1TaskQueueEntry& operator=(const volatile G1TaskQueueEntry& t) volatile { + _holder = t._holder; + return *this; + } + + oop obj() const { + assert(!is_array_slice(), "Trying to read array slice " PTR_FORMAT " as oop", p2i(_holder)); + return (oop)_holder; + } + + HeapWord* slice() const { + assert(is_array_slice(), "Trying to read oop " PTR_FORMAT " as array slice", p2i(_holder)); + return (HeapWord*)((uintptr_t)_holder & ~ArraySliceBit); + } + + bool is_oop() const { return !is_array_slice(); } + bool is_array_slice() const { return ((uintptr_t)_holder & ArraySliceBit) != 0; } + bool is_null() const { return _holder == NULL; } +}; + +#ifdef _MSC_VER +#pragma warning(pop) +#endif + +typedef GenericTaskQueue G1CMTaskQueue; +typedef GenericTaskQueueSet G1CMTaskQueueSet; + +// Closure used by CM during concurrent reference discovery +// and reference processing (during remarking) to determine +// if a particular object is alive. It is primarily used +// to determine if referents of discovered reference objects +// are alive. An instance is also embedded into the +// reference processor as the _is_alive_non_header field +class G1CMIsAliveClosure: public BoolObjectClosure { + G1CollectedHeap* _g1; + public: + G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { } + + bool do_object_b(oop obj); +}; + +// Represents the overflow mark stack used by concurrent marking. +// +// Stores oops in a huge buffer in virtual memory that is always fully committed. +// Resizing may only happen during a STW pause when the stack is empty. +// +// Memory is allocated on a "chunk" basis, i.e. a set of oops. For this, the mark +// stack memory is split into evenly sized chunks of oops. Users can only +// add or remove entries on that basis. +// Chunks are filled in increasing address order. Not completely filled chunks +// have a NULL element as a terminating element. +// +// Every chunk has a header containing a single pointer element used for memory +// management. This wastes some space, but is negligible (< .1% with current sizing). +// +// Memory management is done using a mix of tracking a high water-mark indicating +// that all chunks at a lower address are valid chunks, and a singly linked free +// list connecting all empty chunks. +class G1CMMarkStack VALUE_OBJ_CLASS_SPEC { +public: + // Number of TaskQueueEntries that can fit in a single chunk. + static const size_t EntriesPerChunk = 1024 - 1 /* One reference for the next pointer */; +private: + struct TaskQueueEntryChunk { + TaskQueueEntryChunk* next; + G1TaskQueueEntry data[EntriesPerChunk]; + }; + + size_t _max_chunk_capacity; // Maximum number of TaskQueueEntryChunk elements on the stack. + + TaskQueueEntryChunk* _base; // Bottom address of allocated memory area. + size_t _chunk_capacity; // Current maximum number of TaskQueueEntryChunk elements. + + char _pad0[DEFAULT_CACHE_LINE_SIZE]; + TaskQueueEntryChunk* volatile _free_list; // Linked list of free chunks that can be allocated by users. + char _pad1[DEFAULT_CACHE_LINE_SIZE - sizeof(TaskQueueEntryChunk*)]; + TaskQueueEntryChunk* volatile _chunk_list; // List of chunks currently containing data. + volatile size_t _chunks_in_chunk_list; + char _pad2[DEFAULT_CACHE_LINE_SIZE - sizeof(TaskQueueEntryChunk*) - sizeof(size_t)]; + + volatile size_t _hwm; // High water mark within the reserved space. + char _pad4[DEFAULT_CACHE_LINE_SIZE - sizeof(size_t)]; + + // Allocate a new chunk from the reserved memory, using the high water mark. Returns + // NULL if out of memory. + TaskQueueEntryChunk* allocate_new_chunk(); + + // Atomically add the given chunk to the list. + void add_chunk_to_list(TaskQueueEntryChunk* volatile* list, TaskQueueEntryChunk* elem); + // Atomically remove and return a chunk from the given list. Returns NULL if the + // list is empty. + TaskQueueEntryChunk* remove_chunk_from_list(TaskQueueEntryChunk* volatile* list); + + void add_chunk_to_chunk_list(TaskQueueEntryChunk* elem); + void add_chunk_to_free_list(TaskQueueEntryChunk* elem); + + TaskQueueEntryChunk* remove_chunk_from_chunk_list(); + TaskQueueEntryChunk* remove_chunk_from_free_list(); + + // Resizes the mark stack to the given new capacity. Releases any previous + // memory if successful. + bool resize(size_t new_capacity); + + public: + G1CMMarkStack(); + ~G1CMMarkStack(); + + // Alignment and minimum capacity of this mark stack in number of oops. + static size_t capacity_alignment(); + + // Allocate and initialize the mark stack with the given number of oops. + bool initialize(size_t initial_capacity, size_t max_capacity); + + // Pushes the given buffer containing at most EntriesPerChunk elements on the mark + // stack. If less than EntriesPerChunk elements are to be pushed, the array must + // be terminated with a NULL. + // Returns whether the buffer contents were successfully pushed to the global mark + // stack. + bool par_push_chunk(G1TaskQueueEntry* buffer); + + // Pops a chunk from this mark stack, copying them into the given buffer. This + // chunk may contain up to EntriesPerChunk elements. If there are less, the last + // element in the array is a NULL pointer. + bool par_pop_chunk(G1TaskQueueEntry* buffer); + + // Return whether the chunk list is empty. Racy due to unsynchronized access to + // _chunk_list. + bool is_empty() const { return _chunk_list == NULL; } + + size_t capacity() const { return _chunk_capacity; } + + // Expand the stack, typically in response to an overflow condition + void expand(); + + // Return the approximate number of oops on this mark stack. Racy due to + // unsynchronized access to _chunks_in_chunk_list. + size_t size() const { return _chunks_in_chunk_list * EntriesPerChunk; } + + void set_empty(); + + // Apply Fn to every oop on the mark stack. The mark stack must not + // be modified while iterating. + template void iterate(Fn fn) const PRODUCT_RETURN; +}; + +// Root Regions are regions that are not empty at the beginning of a +// marking cycle and which we might collect during an evacuation pause +// while the cycle is active. Given that, during evacuation pauses, we +// do not copy objects that are explicitly marked, what we have to do +// for the root regions is to scan them and mark all objects reachable +// from them. According to the SATB assumptions, we only need to visit +// each object once during marking. So, as long as we finish this scan +// before the next evacuation pause, we can copy the objects from the +// root regions without having to mark them or do anything else to them. +// +// Currently, we only support root region scanning once (at the start +// of the marking cycle) and the root regions are all the survivor +// regions populated during the initial-mark pause. +class G1CMRootRegions VALUE_OBJ_CLASS_SPEC { +private: + const G1SurvivorRegions* _survivors; + G1ConcurrentMark* _cm; + + volatile bool _scan_in_progress; + volatile bool _should_abort; + volatile int _claimed_survivor_index; + + void notify_scan_done(); + +public: + G1CMRootRegions(); + // We actually do most of the initialization in this method. + void init(const G1SurvivorRegions* survivors, G1ConcurrentMark* cm); + + // Reset the claiming / scanning of the root regions. + void prepare_for_scan(); + + // Forces get_next() to return NULL so that the iteration aborts early. + void abort() { _should_abort = true; } + + // Return true if the CM thread are actively scanning root regions, + // false otherwise. + bool scan_in_progress() { return _scan_in_progress; } + + // Claim the next root region to scan atomically, or return NULL if + // all have been claimed. + HeapRegion* claim_next(); + + // The number of root regions to scan. + uint num_root_regions() const; + + void cancel_scan(); + + // Flag that we're done with root region scanning and notify anyone + // who's waiting on it. If aborted is false, assume that all regions + // have been claimed. + void scan_finished(); + + // If CM threads are still scanning root regions, wait until they + // are done. Return true if we had to wait, false otherwise. + bool wait_until_scan_finished(); +}; + +class ConcurrentMarkThread; + +class G1ConcurrentMark: public CHeapObj { + friend class ConcurrentMarkThread; + friend class G1ParNoteEndTask; + friend class G1VerifyLiveDataClosure; + friend class G1CMRefProcTaskProxy; + friend class G1CMRefProcTaskExecutor; + friend class G1CMKeepAliveAndDrainClosure; + friend class G1CMDrainMarkingStackClosure; + friend class G1CMBitMapClosure; + friend class G1CMConcurrentMarkingTask; + friend class G1CMRemarkTask; + friend class G1CMTask; + +protected: + ConcurrentMarkThread* _cmThread; // The thread doing the work + G1CollectedHeap* _g1h; // The heap + uint _parallel_marking_threads; // The number of marking + // threads we're using + uint _max_parallel_marking_threads; // Max number of marking + // threads we'll ever use + double _sleep_factor; // How much we have to sleep, with + // respect to the work we just did, to + // meet the marking overhead goal + double _marking_task_overhead; // Marking target overhead for + // a single task + + FreeRegionList _cleanup_list; + + // Concurrent marking support structures + G1CMBitMap _markBitMap1; + G1CMBitMap _markBitMap2; + G1CMBitMap* _prevMarkBitMap; // Completed mark bitmap + G1CMBitMap* _nextMarkBitMap; // Under-construction mark bitmap + + // Heap bounds + HeapWord* _heap_start; + HeapWord* _heap_end; + + // Root region tracking and claiming + G1CMRootRegions _root_regions; + + // For gray objects + G1CMMarkStack _global_mark_stack; // Grey objects behind global finger + HeapWord* volatile _finger; // The global finger, region aligned, + // always points to the end of the + // last claimed region + + // Marking tasks + uint _max_worker_id;// Maximum worker id + uint _active_tasks; // Task num currently active + G1CMTask** _tasks; // Task queue array (max_worker_id len) + G1CMTaskQueueSet* _task_queues; // Task queue set + ParallelTaskTerminator _terminator; // For termination + + // Two sync barriers that are used to synchronize tasks when an + // overflow occurs. The algorithm is the following. All tasks enter + // the first one to ensure that they have all stopped manipulating + // the global data structures. After they exit it, they re-initialize + // their data structures and task 0 re-initializes the global data + // structures. Then, they enter the second sync barrier. This + // ensure, that no task starts doing work before all data + // structures (local and global) have been re-initialized. When they + // exit it, they are free to start working again. + WorkGangBarrierSync _first_overflow_barrier_sync; + WorkGangBarrierSync _second_overflow_barrier_sync; + + // This is set by any task, when an overflow on the global data + // structures is detected + volatile bool _has_overflown; + // True: marking is concurrent, false: we're in remark + volatile bool _concurrent; + // Set at the end of a Full GC so that marking aborts + volatile bool _has_aborted; + + // Used when remark aborts due to an overflow to indicate that + // another concurrent marking phase should start + volatile bool _restart_for_overflow; + + // This is true from the very start of concurrent marking until the + // point when all the tasks complete their work. It is really used + // to determine the points between the end of concurrent marking and + // time of remark. + volatile bool _concurrent_marking_in_progress; + + ConcurrentGCTimer* _gc_timer_cm; + + G1OldTracer* _gc_tracer_cm; + + // All of these times are in ms + NumberSeq _init_times; + NumberSeq _remark_times; + NumberSeq _remark_mark_times; + NumberSeq _remark_weak_ref_times; + NumberSeq _cleanup_times; + double _total_counting_time; + double _total_rs_scrub_time; + + double* _accum_task_vtime; // Accumulated task vtime + + WorkGang* _parallel_workers; + + void weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes); + void weakRefsWork(bool clear_all_soft_refs); + + void swapMarkBitMaps(); + + // It resets the global marking data structures, as well as the + // task local ones; should be called during initial mark. + void reset(); + + // Resets all the marking data structures. Called when we have to restart + // marking or when marking completes (via set_non_marking_state below). + void reset_marking_state(); + + // We do this after we're done with marking so that the marking data + // structures are initialized to a sensible and predictable state. + void set_non_marking_state(); + + // Called to indicate how many threads are currently active. + void set_concurrency(uint active_tasks); + + // It should be called to indicate which phase we're in (concurrent + // mark or remark) and how many threads are currently active. + void set_concurrency_and_phase(uint active_tasks, bool concurrent); + + // Prints all gathered CM-related statistics + void print_stats(); + + bool cleanup_list_is_empty() { + return _cleanup_list.is_empty(); + } + + // Accessor methods + uint parallel_marking_threads() const { return _parallel_marking_threads; } + uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;} + double sleep_factor() { return _sleep_factor; } + double marking_task_overhead() { return _marking_task_overhead;} + + HeapWord* finger() { return _finger; } + bool concurrent() { return _concurrent; } + uint active_tasks() { return _active_tasks; } + ParallelTaskTerminator* terminator() { return &_terminator; } + + // It claims the next available region to be scanned by a marking + // task/thread. It might return NULL if the next region is empty or + // we have run out of regions. In the latter case, out_of_regions() + // determines whether we've really run out of regions or the task + // should call claim_region() again. This might seem a bit + // awkward. Originally, the code was written so that claim_region() + // either successfully returned with a non-empty region or there + // were no more regions to be claimed. The problem with this was + // that, in certain circumstances, it iterated over large chunks of + // the heap finding only empty regions and, while it was working, it + // was preventing the calling task to call its regular clock + // method. So, this way, each task will spend very little time in + // claim_region() and is allowed to call the regular clock method + // frequently. + HeapRegion* claim_region(uint worker_id); + + // It determines whether we've run out of regions to scan. Note that + // the finger can point past the heap end in case the heap was expanded + // to satisfy an allocation without doing a GC. This is fine, because all + // objects in those regions will be considered live anyway because of + // SATB guarantees (i.e. their TAMS will be equal to bottom). + bool out_of_regions() { return _finger >= _heap_end; } + + // Returns the task with the given id + G1CMTask* task(int id) { + assert(0 <= id && id < (int) _active_tasks, + "task id not within active bounds"); + return _tasks[id]; + } + + // Returns the task queue with the given id + G1CMTaskQueue* task_queue(int id) { + assert(0 <= id && id < (int) _active_tasks, + "task queue id not within active bounds"); + return (G1CMTaskQueue*) _task_queues->queue(id); + } + + // Returns the task queue set + G1CMTaskQueueSet* task_queues() { return _task_queues; } + + // Access / manipulation of the overflow flag which is set to + // indicate that the global stack has overflown + bool has_overflown() { return _has_overflown; } + void set_has_overflown() { _has_overflown = true; } + void clear_has_overflown() { _has_overflown = false; } + bool restart_for_overflow() { return _restart_for_overflow; } + + // Methods to enter the two overflow sync barriers + void enter_first_sync_barrier(uint worker_id); + void enter_second_sync_barrier(uint worker_id); + + // Card index of the bottom of the G1 heap. Used for biasing indices into + // the card bitmaps. + intptr_t _heap_bottom_card_num; + + // Set to true when initialization is complete + bool _completed_initialization; + + // end_timer, true to end gc timer after ending concurrent phase. + void register_concurrent_phase_end_common(bool end_timer); + + // Clear the given bitmap in parallel using the given WorkGang. If may_yield is + // true, periodically insert checks to see if this method should exit prematurely. + void clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield); +public: + // Manipulation of the global mark stack. + // The push and pop operations are used by tasks for transfers + // between task-local queues and the global mark stack. + bool mark_stack_push(G1TaskQueueEntry* arr) { + if (!_global_mark_stack.par_push_chunk(arr)) { + set_has_overflown(); + return false; + } + return true; + } + bool mark_stack_pop(G1TaskQueueEntry* arr) { + return _global_mark_stack.par_pop_chunk(arr); + } + size_t mark_stack_size() { return _global_mark_stack.size(); } + size_t partial_mark_stack_size_target() { return _global_mark_stack.capacity()/3; } + bool mark_stack_empty() { return _global_mark_stack.is_empty(); } + + G1CMRootRegions* root_regions() { return &_root_regions; } + + bool concurrent_marking_in_progress() { + return _concurrent_marking_in_progress; + } + void set_concurrent_marking_in_progress() { + _concurrent_marking_in_progress = true; + } + void clear_concurrent_marking_in_progress() { + _concurrent_marking_in_progress = false; + } + + void concurrent_cycle_start(); + void concurrent_cycle_end(); + + void update_accum_task_vtime(int i, double vtime) { + _accum_task_vtime[i] += vtime; + } + + double all_task_accum_vtime() { + double ret = 0.0; + for (uint i = 0; i < _max_worker_id; ++i) + ret += _accum_task_vtime[i]; + return ret; + } + + // Attempts to steal an object from the task queues of other tasks + bool try_stealing(uint worker_id, int* hash_seed, G1TaskQueueEntry& task_entry); + + G1ConcurrentMark(G1CollectedHeap* g1h, + G1RegionToSpaceMapper* prev_bitmap_storage, + G1RegionToSpaceMapper* next_bitmap_storage); + ~G1ConcurrentMark(); + + ConcurrentMarkThread* cmThread() { return _cmThread; } + + const G1CMBitMap* const prevMarkBitMap() const { return _prevMarkBitMap; } + G1CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; } + + // Returns the number of GC threads to be used in a concurrent + // phase based on the number of GC threads being used in a STW + // phase. + uint scale_parallel_threads(uint n_par_threads); + + // Calculates the number of GC threads to be used in a concurrent phase. + uint calc_parallel_marking_threads(); + + // Prepare internal data structures for the next mark cycle. This includes clearing + // the next mark bitmap and some internal data structures. This method is intended + // to be called concurrently to the mutator. It will yield to safepoint requests. + void cleanup_for_next_mark(); + + // Clear the previous marking bitmap during safepoint. + void clear_prev_bitmap(WorkGang* workers); + + // Return whether the next mark bitmap has no marks set. To be used for assertions + // only. Will not yield to pause requests. + bool nextMarkBitmapIsClear(); + + // These two do the work that needs to be done before and after the + // initial root checkpoint. Since this checkpoint can be done at two + // different points (i.e. an explicit pause or piggy-backed on a + // young collection), then it's nice to be able to easily share the + // pre/post code. It might be the case that we can put everything in + // the post method. TP + void checkpointRootsInitialPre(); + void checkpointRootsInitialPost(); + + // Scan all the root regions and mark everything reachable from + // them. + void scan_root_regions(); + + // Scan a single root region and mark everything reachable from it. + void scanRootRegion(HeapRegion* hr); + + // Do concurrent phase of marking, to a tentative transitive closure. + void mark_from_roots(); + + void checkpointRootsFinal(bool clear_all_soft_refs); + void checkpointRootsFinalWork(); + void cleanup(); + void complete_cleanup(); + + // Mark in the previous bitmap. NB: this is usually read-only, so use + // this carefully! + inline void markPrev(oop p); + + // Clears marks for all objects in the given range, for the prev or + // next bitmaps. NB: the previous bitmap is usually + // read-only, so use this carefully! + void clearRangePrevBitmap(MemRegion mr); + + // Verify that there are no CSet oops on the stacks (taskqueues / + // global mark stack) and fingers (global / per-task). + // If marking is not in progress, it's a no-op. + void verify_no_cset_oops() PRODUCT_RETURN; + + inline bool isPrevMarked(oop p) const; + + inline bool do_yield_check(); + + // Abandon current marking iteration due to a Full GC. + void abort(); + + bool has_aborted() { return _has_aborted; } + + void print_summary_info(); + + void print_worker_threads_on(outputStream* st) const; + void threads_do(ThreadClosure* tc) const; + + void print_on_error(outputStream* st) const; + + // Mark the given object on the next bitmap if it is below nTAMS. + inline bool mark_in_next_bitmap(HeapRegion* const hr, oop const obj); + inline bool mark_in_next_bitmap(oop const obj); + + // Returns true if initialization was successfully completed. + bool completed_initialization() const { + return _completed_initialization; + } + + ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } + G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } + +private: + // Clear (Reset) all liveness count data. + void clear_live_data(WorkGang* workers); + +#ifdef ASSERT + // Verify all of the above data structures that they are in initial state. + void verify_live_data_clear(); +#endif + + // Aggregates the per-card liveness data based on the current marking. Also sets + // the amount of marked bytes for each region. + void create_live_data(); + + void finalize_live_data(); + + void verify_live_data(); +}; + +// A class representing a marking task. +class G1CMTask : public TerminatorTerminator { +private: + enum PrivateConstants { + // The regular clock call is called once the scanned words reaches + // this limit + words_scanned_period = 12*1024, + // The regular clock call is called once the number of visited + // references reaches this limit + refs_reached_period = 1024, + // Initial value for the hash seed, used in the work stealing code + init_hash_seed = 17 + }; + + G1CMObjArrayProcessor _objArray_processor; + + uint _worker_id; + G1CollectedHeap* _g1h; + G1ConcurrentMark* _cm; + G1CMBitMap* _nextMarkBitMap; + // the task queue of this task + G1CMTaskQueue* _task_queue; +private: + // the task queue set---needed for stealing + G1CMTaskQueueSet* _task_queues; + // indicates whether the task has been claimed---this is only for + // debugging purposes + bool _claimed; + + // number of calls to this task + int _calls; + + // when the virtual timer reaches this time, the marking step should + // exit + double _time_target_ms; + // the start time of the current marking step + double _start_time_ms; + + // the oop closure used for iterations over oops + G1CMOopClosure* _cm_oop_closure; + + // the region this task is scanning, NULL if we're not scanning any + HeapRegion* _curr_region; + // the local finger of this task, NULL if we're not scanning a region + HeapWord* _finger; + // limit of the region this task is scanning, NULL if we're not scanning one + HeapWord* _region_limit; + + // the number of words this task has scanned + size_t _words_scanned; + // When _words_scanned reaches this limit, the regular clock is + // called. Notice that this might be decreased under certain + // circumstances (i.e. when we believe that we did an expensive + // operation). + size_t _words_scanned_limit; + // the initial value of _words_scanned_limit (i.e. what it was + // before it was decreased). + size_t _real_words_scanned_limit; + + // the number of references this task has visited + size_t _refs_reached; + // When _refs_reached reaches this limit, the regular clock is + // called. Notice this this might be decreased under certain + // circumstances (i.e. when we believe that we did an expensive + // operation). + size_t _refs_reached_limit; + // the initial value of _refs_reached_limit (i.e. what it was before + // it was decreased). + size_t _real_refs_reached_limit; + + // used by the work stealing stuff + int _hash_seed; + // if this is true, then the task has aborted for some reason + bool _has_aborted; + // set when the task aborts because it has met its time quota + bool _has_timed_out; + // true when we're draining SATB buffers; this avoids the task + // aborting due to SATB buffers being available (as we're already + // dealing with them) + bool _draining_satb_buffers; + + // number sequence of past step times + NumberSeq _step_times_ms; + // elapsed time of this task + double _elapsed_time_ms; + // termination time of this task + double _termination_time_ms; + // when this task got into the termination protocol + double _termination_start_time_ms; + + // true when the task is during a concurrent phase, false when it is + // in the remark phase (so, in the latter case, we do not have to + // check all the things that we have to check during the concurrent + // phase, i.e. SATB buffer availability...) + bool _concurrent; + + TruncatedSeq _marking_step_diffs_ms; + + // it updates the local fields after this task has claimed + // a new region to scan + void setup_for_region(HeapRegion* hr); + // it brings up-to-date the limit of the region + void update_region_limit(); + + // called when either the words scanned or the refs visited limit + // has been reached + void reached_limit(); + // recalculates the words scanned and refs visited limits + void recalculate_limits(); + // decreases the words scanned and refs visited limits when we reach + // an expensive operation + void decrease_limits(); + // it checks whether the words scanned or refs visited reached their + // respective limit and calls reached_limit() if they have + void check_limits() { + if (_words_scanned >= _words_scanned_limit || + _refs_reached >= _refs_reached_limit) { + reached_limit(); + } + } + // this is supposed to be called regularly during a marking step as + // it checks a bunch of conditions that might cause the marking step + // to abort + void regular_clock_call(); + bool concurrent() { return _concurrent; } + + // Test whether obj might have already been passed over by the + // mark bitmap scan, and so needs to be pushed onto the mark stack. + bool is_below_finger(oop obj, HeapWord* global_finger) const; + + template void process_grey_task_entry(G1TaskQueueEntry task_entry); +public: + // Apply the closure on the given area of the objArray. Return the number of words + // scanned. + inline size_t scan_objArray(objArrayOop obj, MemRegion mr); + // It resets the task; it should be called right at the beginning of + // a marking phase. + void reset(G1CMBitMap* _nextMarkBitMap); + // it clears all the fields that correspond to a claimed region. + void clear_region_fields(); + + void set_concurrent(bool concurrent) { _concurrent = concurrent; } + + // The main method of this class which performs a marking step + // trying not to exceed the given duration. However, it might exit + // prematurely, according to some conditions (i.e. SATB buffers are + // available for processing). + void do_marking_step(double target_ms, + bool do_termination, + bool is_serial); + + // These two calls start and stop the timer + void record_start_time() { + _elapsed_time_ms = os::elapsedTime() * 1000.0; + } + void record_end_time() { + _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms; + } + + // returns the worker ID associated with this task. + uint worker_id() { return _worker_id; } + + // From TerminatorTerminator. It determines whether this task should + // exit the termination protocol after it's entered it. + virtual bool should_exit_termination(); + + // Resets the local region fields after a task has finished scanning a + // region; or when they have become stale as a result of the region + // being evacuated. + void giveup_current_region(); + + HeapWord* finger() { return _finger; } + + bool has_aborted() { return _has_aborted; } + void set_has_aborted() { _has_aborted = true; } + void clear_has_aborted() { _has_aborted = false; } + bool has_timed_out() { return _has_timed_out; } + bool claimed() { return _claimed; } + + void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure); + + // Increment the number of references this task has visited. + void increment_refs_reached() { ++_refs_reached; } + + // Grey the object by marking it. If not already marked, push it on + // the local queue if below the finger. + // obj is below its region's NTAMS. + inline void make_reference_grey(oop obj); + + // Grey the object (by calling make_grey_reference) if required, + // e.g. obj is below its containing region's NTAMS. + // Precondition: obj is a valid heap object. + inline void deal_with_reference(oop obj); + + // It scans an object and visits its children. + inline void scan_task_entry(G1TaskQueueEntry task_entry); + + // It pushes an object on the local queue. + inline void push(G1TaskQueueEntry task_entry); + + // Move entries to the global stack. + void move_entries_to_global_stack(); + // Move entries from the global stack, return true if we were successful to do so. + bool get_entries_from_global_stack(); + + // It pops and scans objects from the local queue. If partially is + // true, then it stops when the queue size is of a given limit. If + // partially is false, then it stops when the queue is empty. + void drain_local_queue(bool partially); + // It moves entries from the global stack to the local queue and + // drains the local queue. If partially is true, then it stops when + // both the global stack and the local queue reach a given size. If + // partially if false, it tries to empty them totally. + void drain_global_stack(bool partially); + // It keeps picking SATB buffers and processing them until no SATB + // buffers are available. + void drain_satb_buffers(); + + // moves the local finger to a new location + inline void move_finger_to(HeapWord* new_finger) { + assert(new_finger >= _finger && new_finger < _region_limit, "invariant"); + _finger = new_finger; + } + + G1CMTask(uint worker_id, + G1ConcurrentMark *cm, + G1CMTaskQueue* task_queue, + G1CMTaskQueueSet* task_queues); + + // it prints statistics associated with this task + void print_stats(); +}; + +// Class that's used to to print out per-region liveness +// information. It's currently used at the end of marking and also +// after we sort the old regions at the end of the cleanup operation. +class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure { +private: + // Accumulators for these values. + size_t _total_used_bytes; + size_t _total_capacity_bytes; + size_t _total_prev_live_bytes; + size_t _total_next_live_bytes; + + // Accumulator for the remembered set size + size_t _total_remset_bytes; + + // Accumulator for strong code roots memory size + size_t _total_strong_code_roots_bytes; + + static double perc(size_t val, size_t total) { + if (total == 0) { + return 0.0; + } else { + return 100.0 * ((double) val / (double) total); + } + } + + static double bytes_to_mb(size_t val) { + return (double) val / (double) M; + } + +public: + // The header and footer are printed in the constructor and + // destructor respectively. + G1PrintRegionLivenessInfoClosure(const char* phase_name); + virtual bool doHeapRegion(HeapRegion* r); + ~G1PrintRegionLivenessInfoClosure(); +}; + +#endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP