--- /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<G1TaskQueueEntry, mtGC> G1CMTaskQueue;
+typedef GenericTaskQueueSet<G1CMTaskQueue, mtGC> 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<typename Fn> 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<mtGC> {
+ 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<bool scan> 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