1071 lines
40 KiB
C++
1071 lines
40 KiB
C++
/*
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* Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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class G1CollectedHeap;
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class CMTask;
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typedef GenericTaskQueue<oop> CMTaskQueue;
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typedef GenericTaskQueueSet<CMTaskQueue> CMTaskQueueSet;
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// A generic CM bit map. This is essentially a wrapper around the BitMap
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// class, with one bit per (1<<_shifter) HeapWords.
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class CMBitMapRO VALUE_OBJ_CLASS_SPEC {
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protected:
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HeapWord* _bmStartWord; // base address of range covered by map
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size_t _bmWordSize; // map size (in #HeapWords covered)
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const int _shifter; // map to char or bit
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VirtualSpace _virtual_space; // underlying the bit map
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BitMap _bm; // the bit map itself
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public:
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// constructor
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CMBitMapRO(ReservedSpace rs, int shifter);
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enum { do_yield = true };
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// inquiries
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HeapWord* startWord() const { return _bmStartWord; }
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size_t sizeInWords() const { return _bmWordSize; }
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// the following is one past the last word in space
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HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
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// read marks
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bool isMarked(HeapWord* addr) const {
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assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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"outside underlying space?");
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return _bm.at(heapWordToOffset(addr));
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}
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// iteration
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bool iterate(BitMapClosure* cl) { return _bm.iterate(cl); }
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bool iterate(BitMapClosure* cl, MemRegion mr);
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// Return the address corresponding to the next marked bit at or after
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// "addr", and before "limit", if "limit" is non-NULL. If there is no
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// such bit, returns "limit" if that is non-NULL, or else "endWord()".
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HeapWord* getNextMarkedWordAddress(HeapWord* addr,
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HeapWord* limit = NULL) const;
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// Return the address corresponding to the next unmarked bit at or after
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// "addr", and before "limit", if "limit" is non-NULL. If there is no
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// such bit, returns "limit" if that is non-NULL, or else "endWord()".
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HeapWord* getNextUnmarkedWordAddress(HeapWord* addr,
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HeapWord* limit = NULL) const;
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// conversion utilities
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// XXX Fix these so that offsets are size_t's...
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HeapWord* offsetToHeapWord(size_t offset) const {
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return _bmStartWord + (offset << _shifter);
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}
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size_t heapWordToOffset(HeapWord* addr) const {
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return pointer_delta(addr, _bmStartWord) >> _shifter;
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}
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int heapWordDiffToOffsetDiff(size_t diff) const;
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HeapWord* nextWord(HeapWord* addr) {
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return offsetToHeapWord(heapWordToOffset(addr) + 1);
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}
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void mostly_disjoint_range_union(BitMap* from_bitmap,
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size_t from_start_index,
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HeapWord* to_start_word,
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size_t word_num);
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// debugging
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NOT_PRODUCT(bool covers(ReservedSpace rs) const;)
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};
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class CMBitMap : public CMBitMapRO {
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public:
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// constructor
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CMBitMap(ReservedSpace rs, int shifter) :
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CMBitMapRO(rs, shifter) {}
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// write marks
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void mark(HeapWord* addr) {
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assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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"outside underlying space?");
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_bm.at_put(heapWordToOffset(addr), true);
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}
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void clear(HeapWord* addr) {
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assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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"outside underlying space?");
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_bm.at_put(heapWordToOffset(addr), false);
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}
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bool parMark(HeapWord* addr) {
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assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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"outside underlying space?");
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return _bm.par_at_put(heapWordToOffset(addr), true);
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}
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bool parClear(HeapWord* addr) {
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assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
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"outside underlying space?");
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return _bm.par_at_put(heapWordToOffset(addr), false);
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}
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void markRange(MemRegion mr);
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void clearAll();
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void clearRange(MemRegion mr);
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// Starting at the bit corresponding to "addr" (inclusive), find the next
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// "1" bit, if any. This bit starts some run of consecutive "1"'s; find
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// the end of this run (stopping at "end_addr"). Return the MemRegion
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// covering from the start of the region corresponding to the first bit
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// of the run to the end of the region corresponding to the last bit of
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// the run. If there is no "1" bit at or after "addr", return an empty
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// MemRegion.
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MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
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};
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// Represents a marking stack used by the CM collector.
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// Ideally this should be GrowableArray<> just like MSC's marking stack(s).
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class CMMarkStack VALUE_OBJ_CLASS_SPEC {
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ConcurrentMark* _cm;
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oop* _base; // bottom of stack
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jint _index; // one more than last occupied index
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jint _capacity; // max #elements
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jint _oops_do_bound; // Number of elements to include in next iteration.
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NOT_PRODUCT(jint _max_depth;) // max depth plumbed during run
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bool _overflow;
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DEBUG_ONLY(bool _drain_in_progress;)
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DEBUG_ONLY(bool _drain_in_progress_yields;)
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public:
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CMMarkStack(ConcurrentMark* cm);
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~CMMarkStack();
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void allocate(size_t size);
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oop pop() {
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if (!isEmpty()) {
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return _base[--_index] ;
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}
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return NULL;
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}
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// If overflow happens, don't do the push, and record the overflow.
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// *Requires* that "ptr" is already marked.
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void push(oop ptr) {
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if (isFull()) {
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// Record overflow.
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_overflow = true;
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return;
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} else {
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_base[_index++] = ptr;
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NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));
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}
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}
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// Non-block impl. Note: concurrency is allowed only with other
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// "par_push" operations, not with "pop" or "drain". We would need
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// parallel versions of them if such concurrency was desired.
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void par_push(oop ptr);
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// Pushes the first "n" elements of "ptr_arr" on the stack.
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// Non-block impl. Note: concurrency is allowed only with other
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// "par_adjoin_arr" or "push" operations, not with "pop" or "drain".
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void par_adjoin_arr(oop* ptr_arr, int n);
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// Pushes the first "n" elements of "ptr_arr" on the stack.
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// Locking impl: concurrency is allowed only with
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// "par_push_arr" and/or "par_pop_arr" operations, which use the same
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// locking strategy.
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void par_push_arr(oop* ptr_arr, int n);
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// If returns false, the array was empty. Otherwise, removes up to "max"
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// elements from the stack, and transfers them to "ptr_arr" in an
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// unspecified order. The actual number transferred is given in "n" ("n
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// == 0" is deliberately redundant with the return value.) Locking impl:
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// concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
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// operations, which use the same locking strategy.
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bool par_pop_arr(oop* ptr_arr, int max, int* n);
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// Drain the mark stack, applying the given closure to all fields of
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// objects on the stack. (That is, continue until the stack is empty,
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// even if closure applications add entries to the stack.) The "bm"
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// argument, if non-null, may be used to verify that only marked objects
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// are on the mark stack. If "yield_after" is "true", then the
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// concurrent marker performing the drain offers to yield after
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// processing each object. If a yield occurs, stops the drain operation
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// and returns false. Otherwise, returns true.
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template<class OopClosureClass>
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bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);
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bool isEmpty() { return _index == 0; }
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bool isFull() { return _index == _capacity; }
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int maxElems() { return _capacity; }
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bool overflow() { return _overflow; }
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void clear_overflow() { _overflow = false; }
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int size() { return _index; }
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void setEmpty() { _index = 0; clear_overflow(); }
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// Record the current size; a subsequent "oops_do" will iterate only over
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// indices valid at the time of this call.
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void set_oops_do_bound(jint bound = -1) {
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if (bound == -1) {
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_oops_do_bound = _index;
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} else {
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_oops_do_bound = bound;
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}
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}
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jint oops_do_bound() { return _oops_do_bound; }
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// iterate over the oops in the mark stack, up to the bound recorded via
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// the call above.
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void oops_do(OopClosure* f);
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};
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class CMRegionStack VALUE_OBJ_CLASS_SPEC {
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MemRegion* _base;
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jint _capacity;
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jint _index;
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jint _oops_do_bound;
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bool _overflow;
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public:
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CMRegionStack();
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~CMRegionStack();
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void allocate(size_t size);
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// This is lock-free; assumes that it will only be called in parallel
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// with other "push" operations (no pops).
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void push(MemRegion mr);
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#if 0
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// This is currently not used. See the comment in the .cpp file.
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// Lock-free; assumes that it will only be called in parallel
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// with other "pop" operations (no pushes).
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MemRegion pop();
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#endif // 0
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// These two are the implementations that use a lock. They can be
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// called concurrently with each other but they should not be called
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// concurrently with the lock-free versions (push() / pop()).
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void push_with_lock(MemRegion mr);
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MemRegion pop_with_lock();
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bool isEmpty() { return _index == 0; }
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bool isFull() { return _index == _capacity; }
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bool overflow() { return _overflow; }
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void clear_overflow() { _overflow = false; }
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int size() { return _index; }
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// It iterates over the entries in the region stack and it
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// invalidates (i.e. assigns MemRegion()) the ones that point to
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// regions in the collection set.
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bool invalidate_entries_into_cset();
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// This gives an upper bound up to which the iteration in
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// invalidate_entries_into_cset() will reach. This prevents
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// newly-added entries to be unnecessarily scanned.
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void set_oops_do_bound() {
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_oops_do_bound = _index;
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}
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void setEmpty() { _index = 0; clear_overflow(); }
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};
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// this will enable a variety of different statistics per GC task
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#define _MARKING_STATS_ 0
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// this will enable the higher verbose levels
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#define _MARKING_VERBOSE_ 0
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#if _MARKING_STATS_
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#define statsOnly(statement) \
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do { \
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statement ; \
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} while (0)
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#else // _MARKING_STATS_
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#define statsOnly(statement) \
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do { \
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} while (0)
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#endif // _MARKING_STATS_
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typedef enum {
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no_verbose = 0, // verbose turned off
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stats_verbose, // only prints stats at the end of marking
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low_verbose, // low verbose, mostly per region and per major event
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medium_verbose, // a bit more detailed than low
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high_verbose // per object verbose
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} CMVerboseLevel;
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class ConcurrentMarkThread;
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class ConcurrentMark: public CHeapObj {
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friend class ConcurrentMarkThread;
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friend class CMTask;
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friend class CMBitMapClosure;
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friend class CSMarkOopClosure;
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friend class CMGlobalObjectClosure;
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friend class CMRemarkTask;
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friend class CMConcurrentMarkingTask;
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friend class G1ParNoteEndTask;
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friend class CalcLiveObjectsClosure;
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protected:
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ConcurrentMarkThread* _cmThread; // the thread doing the work
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G1CollectedHeap* _g1h; // the heap.
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size_t _parallel_marking_threads; // the number of marking
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// threads we'll use
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double _sleep_factor; // how much we have to sleep, with
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// respect to the work we just did, to
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// meet the marking overhead goal
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double _marking_task_overhead; // marking target overhead for
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// a single task
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// same as the two above, but for the cleanup task
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double _cleanup_sleep_factor;
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double _cleanup_task_overhead;
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// Stuff related to age cohort processing.
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struct ParCleanupThreadState {
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char _pre[64];
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UncleanRegionList list;
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char _post[64];
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};
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ParCleanupThreadState** _par_cleanup_thread_state;
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// CMS marking support structures
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CMBitMap _markBitMap1;
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CMBitMap _markBitMap2;
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CMBitMapRO* _prevMarkBitMap; // completed mark bitmap
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CMBitMap* _nextMarkBitMap; // under-construction mark bitmap
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bool _at_least_one_mark_complete;
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BitMap _region_bm;
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BitMap _card_bm;
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// Heap bounds
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HeapWord* _heap_start;
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HeapWord* _heap_end;
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// For gray objects
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CMMarkStack _markStack; // Grey objects behind global finger.
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CMRegionStack _regionStack; // Grey regions behind global finger.
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HeapWord* volatile _finger; // the global finger, region aligned,
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// always points to the end of the
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// last claimed region
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// marking tasks
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size_t _max_task_num; // maximum task number
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size_t _active_tasks; // task num currently active
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CMTask** _tasks; // task queue array (max_task_num len)
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CMTaskQueueSet* _task_queues; // task queue set
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ParallelTaskTerminator _terminator; // for termination
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// Two sync barriers that are used to synchronise tasks when an
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// overflow occurs. The algorithm is the following. All tasks enter
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// the first one to ensure that they have all stopped manipulating
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// the global data structures. After they exit it, they re-initialise
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// their data structures and task 0 re-initialises the global data
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// structures. Then, they enter the second sync barrier. This
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// ensure, that no task starts doing work before all data
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// structures (local and global) have been re-initialised. When they
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// exit it, they are free to start working again.
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WorkGangBarrierSync _first_overflow_barrier_sync;
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WorkGangBarrierSync _second_overflow_barrier_sync;
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// this is set by any task, when an overflow on the global data
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// structures is detected.
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volatile bool _has_overflown;
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// true: marking is concurrent, false: we're in remark
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volatile bool _concurrent;
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// set at the end of a Full GC so that marking aborts
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volatile bool _has_aborted;
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// used when remark aborts due to an overflow to indicate that
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// another concurrent marking phase should start
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volatile bool _restart_for_overflow;
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// This is true from the very start of concurrent marking until the
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// point when all the tasks complete their work. It is really used
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// to determine the points between the end of concurrent marking and
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// time of remark.
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volatile bool _concurrent_marking_in_progress;
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// verbose level
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CMVerboseLevel _verbose_level;
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// These two fields are used to implement the optimisation that
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// avoids pushing objects on the global/region stack if there are
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// no collection set regions above the lowest finger.
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// This is the lowest finger (among the global and local fingers),
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// which is calculated before a new collection set is chosen.
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HeapWord* _min_finger;
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// If this flag is true, objects/regions that are marked below the
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// finger should be pushed on the stack(s). If this is flag is
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// false, it is safe not to push them on the stack(s).
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bool _should_gray_objects;
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// All of these times are in ms.
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NumberSeq _init_times;
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NumberSeq _remark_times;
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NumberSeq _remark_mark_times;
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NumberSeq _remark_weak_ref_times;
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NumberSeq _cleanup_times;
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double _total_counting_time;
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double _total_rs_scrub_time;
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double* _accum_task_vtime; // accumulated task vtime
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WorkGang* _parallel_workers;
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void weakRefsWork(bool clear_all_soft_refs);
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void swapMarkBitMaps();
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// It resets the global marking data structures, as well as the
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// task local ones; should be called during initial mark.
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void reset();
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// It resets all the marking data structures.
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void clear_marking_state();
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// It should be called to indicate which phase we're in (concurrent
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// mark or remark) and how many threads are currently active.
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void set_phase(size_t active_tasks, bool concurrent);
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// We do this after we're done with marking so that the marking data
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// structures are initialised to a sensible and predictable state.
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void set_non_marking_state();
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// prints all gathered CM-related statistics
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void print_stats();
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// accessor methods
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size_t parallel_marking_threads() { return _parallel_marking_threads; }
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double sleep_factor() { return _sleep_factor; }
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double marking_task_overhead() { return _marking_task_overhead;}
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double cleanup_sleep_factor() { return _cleanup_sleep_factor; }
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double cleanup_task_overhead() { return _cleanup_task_overhead;}
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HeapWord* finger() { return _finger; }
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bool concurrent() { return _concurrent; }
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size_t active_tasks() { return _active_tasks; }
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ParallelTaskTerminator* terminator() { return &_terminator; }
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// It claims the next available region to be scanned by a marking
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// task. It might return NULL if the next region is empty or we have
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// run out of regions. In the latter case, out_of_regions()
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// determines whether we've really run out of regions or the task
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// should call claim_region() again. This might seem a bit
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// awkward. Originally, the code was written so that claim_region()
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// either successfully returned with a non-empty region or there
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// were no more regions to be claimed. The problem with this was
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// that, in certain circumstances, it iterated over large chunks of
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// the heap finding only empty regions and, while it was working, it
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// was preventing the calling task to call its regular clock
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// method. So, this way, each task will spend very little time in
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// claim_region() and is allowed to call the regular clock method
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|
// frequently.
|
|
HeapRegion* claim_region(int task);
|
|
|
|
// It determines whether we've run out of regions to scan.
|
|
bool out_of_regions() { return _finger == _heap_end; }
|
|
|
|
// Returns the task with the given id
|
|
CMTask* 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
|
|
CMTaskQueue* task_queue(int id) {
|
|
assert(0 <= id && id < (int) _active_tasks,
|
|
"task queue id not within active bounds");
|
|
return (CMTaskQueue*) _task_queues->queue(id);
|
|
}
|
|
|
|
// Returns the task queue set
|
|
CMTaskQueueSet* task_queues() { return _task_queues; }
|
|
|
|
// Access / manipulation of the overflow flag which is set to
|
|
// indicate that the global stack or region stack has overflown
|
|
bool has_overflown() { return _has_overflown; }
|
|
void set_has_overflown() { _has_overflown = true; }
|
|
void clear_has_overflown() { _has_overflown = false; }
|
|
|
|
bool has_aborted() { return _has_aborted; }
|
|
bool restart_for_overflow() { return _restart_for_overflow; }
|
|
|
|
// Methods to enter the two overflow sync barriers
|
|
void enter_first_sync_barrier(int task_num);
|
|
void enter_second_sync_barrier(int task_num);
|
|
|
|
public:
|
|
// Manipulation of the global mark stack.
|
|
// Notice that the first mark_stack_push is CAS-based, whereas the
|
|
// two below are Mutex-based. This is OK since the first one is only
|
|
// called during evacuation pauses and doesn't compete with the
|
|
// other two (which are called by the marking tasks during
|
|
// concurrent marking or remark).
|
|
bool mark_stack_push(oop p) {
|
|
_markStack.par_push(p);
|
|
if (_markStack.overflow()) {
|
|
set_has_overflown();
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
bool mark_stack_push(oop* arr, int n) {
|
|
_markStack.par_push_arr(arr, n);
|
|
if (_markStack.overflow()) {
|
|
set_has_overflown();
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
void mark_stack_pop(oop* arr, int max, int* n) {
|
|
_markStack.par_pop_arr(arr, max, n);
|
|
}
|
|
size_t mark_stack_size() { return _markStack.size(); }
|
|
size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
|
|
bool mark_stack_overflow() { return _markStack.overflow(); }
|
|
bool mark_stack_empty() { return _markStack.isEmpty(); }
|
|
|
|
// Manipulation of the region stack
|
|
bool region_stack_push(MemRegion mr) {
|
|
// Currently we only call the lock-free version during evacuation
|
|
// pauses.
|
|
assert(SafepointSynchronize::is_at_safepoint(), "world should be stopped");
|
|
|
|
_regionStack.push(mr);
|
|
if (_regionStack.overflow()) {
|
|
set_has_overflown();
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
#if 0
|
|
// Currently this is not used. See the comment in the .cpp file.
|
|
MemRegion region_stack_pop() { return _regionStack.pop(); }
|
|
#endif // 0
|
|
|
|
bool region_stack_push_with_lock(MemRegion mr) {
|
|
// Currently we only call the lock-based version during either
|
|
// concurrent marking or remark.
|
|
assert(!SafepointSynchronize::is_at_safepoint() || !concurrent(),
|
|
"if we are at a safepoint it should be the remark safepoint");
|
|
|
|
_regionStack.push_with_lock(mr);
|
|
if (_regionStack.overflow()) {
|
|
set_has_overflown();
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
MemRegion region_stack_pop_with_lock() {
|
|
// Currently we only call the lock-based version during either
|
|
// concurrent marking or remark.
|
|
assert(!SafepointSynchronize::is_at_safepoint() || !concurrent(),
|
|
"if we are at a safepoint it should be the remark safepoint");
|
|
|
|
return _regionStack.pop_with_lock();
|
|
}
|
|
|
|
int region_stack_size() { return _regionStack.size(); }
|
|
bool region_stack_overflow() { return _regionStack.overflow(); }
|
|
bool region_stack_empty() { return _regionStack.isEmpty(); }
|
|
|
|
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 update_accum_task_vtime(int i, double vtime) {
|
|
_accum_task_vtime[i] += vtime;
|
|
}
|
|
|
|
double all_task_accum_vtime() {
|
|
double ret = 0.0;
|
|
for (int i = 0; i < (int)_max_task_num; ++i)
|
|
ret += _accum_task_vtime[i];
|
|
return ret;
|
|
}
|
|
|
|
// Attempts to steal an object from the task queues of other tasks
|
|
bool try_stealing(int task_num, int* hash_seed, oop& obj) {
|
|
return _task_queues->steal(task_num, hash_seed, obj);
|
|
}
|
|
|
|
// It grays an object by first marking it. Then, if it's behind the
|
|
// global finger, it also pushes it on the global stack.
|
|
void deal_with_reference(oop obj);
|
|
|
|
ConcurrentMark(ReservedSpace rs, int max_regions);
|
|
~ConcurrentMark();
|
|
ConcurrentMarkThread* cmThread() { return _cmThread; }
|
|
|
|
CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
|
|
CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
|
|
|
|
// The following three are interaction between CM and
|
|
// G1CollectedHeap
|
|
|
|
// This notifies CM that a root during initial-mark needs to be
|
|
// grayed and it's MT-safe. Currently, we just mark it. But, in the
|
|
// future, we can experiment with pushing it on the stack and we can
|
|
// do this without changing G1CollectedHeap.
|
|
void grayRoot(oop p);
|
|
// It's used during evacuation pauses to gray a region, if
|
|
// necessary, and it's MT-safe. It assumes that the caller has
|
|
// marked any objects on that region. If _should_gray_objects is
|
|
// true and we're still doing concurrent marking, the region is
|
|
// pushed on the region stack, if it is located below the global
|
|
// finger, otherwise we do nothing.
|
|
void grayRegionIfNecessary(MemRegion mr);
|
|
// It's used during evacuation pauses to mark and, if necessary,
|
|
// gray a single object and it's MT-safe. It assumes the caller did
|
|
// not mark the object. If _should_gray_objects is true and we're
|
|
// still doing concurrent marking, the objects is pushed on the
|
|
// global stack, if it is located below the global finger, otherwise
|
|
// we do nothing.
|
|
void markAndGrayObjectIfNecessary(oop p);
|
|
|
|
// It iterates over the heap and for each object it comes across it
|
|
// will dump the contents of its reference fields, as well as
|
|
// liveness information for the object and its referents. The dump
|
|
// will be written to a file with the following name:
|
|
// G1PrintReachableBaseFile + "." + str. use_prev_marking decides
|
|
// whether the prev (use_prev_marking == true) or next
|
|
// (use_prev_marking == false) marking information will be used to
|
|
// determine the liveness of each object / referent. If all is true,
|
|
// all objects in the heap will be dumped, otherwise only the live
|
|
// ones. In the dump the following symbols / abbreviations are used:
|
|
// M : an explicitly live object (its bitmap bit is set)
|
|
// > : an implicitly live object (over tams)
|
|
// O : an object outside the G1 heap (typically: in the perm gen)
|
|
// NOT : a reference field whose referent is not live
|
|
// AND MARKED : indicates that an object is both explicitly and
|
|
// implicitly live (it should be one or the other, not both)
|
|
void print_reachable(const char* str,
|
|
bool use_prev_marking, bool all) PRODUCT_RETURN;
|
|
|
|
// Clear the next marking bitmap (will be called concurrently).
|
|
void clearNextBitmap();
|
|
|
|
// main CMS steps and related support
|
|
void checkpointRootsInitial();
|
|
|
|
// 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();
|
|
|
|
// Do concurrent phase of marking, to a tentative transitive closure.
|
|
void markFromRoots();
|
|
|
|
// Process all unprocessed SATB buffers. It is called at the
|
|
// beginning of an evacuation pause.
|
|
void drainAllSATBBuffers();
|
|
|
|
void checkpointRootsFinal(bool clear_all_soft_refs);
|
|
void checkpointRootsFinalWork();
|
|
void calcDesiredRegions();
|
|
void cleanup();
|
|
void completeCleanup();
|
|
|
|
// Mark in the previous bitmap. NB: this is usually read-only, so use
|
|
// this carefully!
|
|
void markPrev(oop p);
|
|
void clear(oop p);
|
|
// Clears marks for all objects in the given range, for both prev and
|
|
// next bitmaps. NB: the previous bitmap is usually read-only, so use
|
|
// this carefully!
|
|
void clearRangeBothMaps(MemRegion mr);
|
|
|
|
// Record the current top of the mark and region stacks; a
|
|
// subsequent oops_do() on the mark stack and
|
|
// invalidate_entries_into_cset() on the region stack will iterate
|
|
// only over indices valid at the time of this call.
|
|
void set_oops_do_bound() {
|
|
_markStack.set_oops_do_bound();
|
|
_regionStack.set_oops_do_bound();
|
|
}
|
|
// Iterate over the oops in the mark stack and all local queues. It
|
|
// also calls invalidate_entries_into_cset() on the region stack.
|
|
void oops_do(OopClosure* f);
|
|
// It is called at the end of an evacuation pause during marking so
|
|
// that CM is notified of where the new end of the heap is. It
|
|
// doesn't do anything if concurrent_marking_in_progress() is false,
|
|
// unless the force parameter is true.
|
|
void update_g1_committed(bool force = false);
|
|
|
|
void complete_marking_in_collection_set();
|
|
|
|
// It indicates that a new collection set is being chosen.
|
|
void newCSet();
|
|
// It registers a collection set heap region with CM. This is used
|
|
// to determine whether any heap regions are located above the finger.
|
|
void registerCSetRegion(HeapRegion* hr);
|
|
|
|
// Returns "true" if at least one mark has been completed.
|
|
bool at_least_one_mark_complete() { return _at_least_one_mark_complete; }
|
|
|
|
bool isMarked(oop p) const {
|
|
assert(p != NULL && p->is_oop(), "expected an oop");
|
|
HeapWord* addr = (HeapWord*)p;
|
|
assert(addr >= _nextMarkBitMap->startWord() ||
|
|
addr < _nextMarkBitMap->endWord(), "in a region");
|
|
|
|
return _nextMarkBitMap->isMarked(addr);
|
|
}
|
|
|
|
inline bool not_yet_marked(oop p) const;
|
|
|
|
// XXX Debug code
|
|
bool containing_card_is_marked(void* p);
|
|
bool containing_cards_are_marked(void* start, void* last);
|
|
|
|
bool isPrevMarked(oop p) const {
|
|
assert(p != NULL && p->is_oop(), "expected an oop");
|
|
HeapWord* addr = (HeapWord*)p;
|
|
assert(addr >= _prevMarkBitMap->startWord() ||
|
|
addr < _prevMarkBitMap->endWord(), "in a region");
|
|
|
|
return _prevMarkBitMap->isMarked(addr);
|
|
}
|
|
|
|
inline bool do_yield_check(int worker_i = 0);
|
|
inline bool should_yield();
|
|
|
|
// Called to abort the marking cycle after a Full GC takes palce.
|
|
void abort();
|
|
|
|
// This prints the global/local fingers. It is used for debugging.
|
|
NOT_PRODUCT(void print_finger();)
|
|
|
|
void print_summary_info();
|
|
|
|
void print_worker_threads_on(outputStream* st) const;
|
|
|
|
// The following indicate whether a given verbose level has been
|
|
// set. Notice that anything above stats is conditional to
|
|
// _MARKING_VERBOSE_ having been set to 1
|
|
bool verbose_stats()
|
|
{ return _verbose_level >= stats_verbose; }
|
|
bool verbose_low()
|
|
{ return _MARKING_VERBOSE_ && _verbose_level >= low_verbose; }
|
|
bool verbose_medium()
|
|
{ return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose; }
|
|
bool verbose_high()
|
|
{ return _MARKING_VERBOSE_ && _verbose_level >= high_verbose; }
|
|
};
|
|
|
|
// A class representing a marking task.
|
|
class CMTask : 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 = 384,
|
|
// initial value for the hash seed, used in the work stealing code
|
|
init_hash_seed = 17,
|
|
// how many entries will be transferred between global stack and
|
|
// local queues
|
|
global_stack_transfer_size = 16
|
|
};
|
|
|
|
int _task_id;
|
|
G1CollectedHeap* _g1h;
|
|
ConcurrentMark* _cm;
|
|
CMBitMap* _nextMarkBitMap;
|
|
// the task queue of this task
|
|
CMTaskQueue* _task_queue;
|
|
private:
|
|
// the task queue set---needed for stealing
|
|
CMTaskQueueSet* _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
|
|
OopClosure* _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;
|
|
|
|
// This is used only when we scan regions popped from the region
|
|
// stack. It records what the last object on such a region we
|
|
// scanned was. It is used to ensure that, if we abort region
|
|
// iteration, we do not rescan the first part of the region. This
|
|
// should be NULL when we're not scanning a region from the region
|
|
// stack.
|
|
HeapWord* _region_finger;
|
|
|
|
// 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_aborted_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;
|
|
|
|
// LOTS of statistics related with this task
|
|
#if _MARKING_STATS_
|
|
NumberSeq _all_clock_intervals_ms;
|
|
double _interval_start_time_ms;
|
|
|
|
int _aborted;
|
|
int _aborted_overflow;
|
|
int _aborted_cm_aborted;
|
|
int _aborted_yield;
|
|
int _aborted_timed_out;
|
|
int _aborted_satb;
|
|
int _aborted_termination;
|
|
|
|
int _steal_attempts;
|
|
int _steals;
|
|
|
|
int _clock_due_to_marking;
|
|
int _clock_due_to_scanning;
|
|
|
|
int _local_pushes;
|
|
int _local_pops;
|
|
int _local_max_size;
|
|
int _objs_scanned;
|
|
|
|
int _global_pushes;
|
|
int _global_pops;
|
|
int _global_max_size;
|
|
|
|
int _global_transfers_to;
|
|
int _global_transfers_from;
|
|
|
|
int _region_stack_pops;
|
|
|
|
int _regions_claimed;
|
|
int _objs_found_on_bitmap;
|
|
|
|
int _satb_buffers_processed;
|
|
#endif // _MARKING_STATS_
|
|
|
|
// 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();
|
|
// it resets the local fields after a task has finished scanning a
|
|
// region
|
|
void giveup_current_region();
|
|
|
|
// 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; }
|
|
|
|
public:
|
|
// It resets the task; it should be called right at the beginning of
|
|
// a marking phase.
|
|
void reset(CMBitMap* _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
|
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// trying not to exceed the given duration. However, it might exit
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// prematurely, according to some conditions (i.e. SATB buffers are
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// available for processing).
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void do_marking_step(double target_ms);
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// These two calls start and stop the timer
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void record_start_time() {
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_elapsed_time_ms = os::elapsedTime() * 1000.0;
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}
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void record_end_time() {
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_elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
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}
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// returns the task ID
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int task_id() { return _task_id; }
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// From TerminatorTerminator. It determines whether this task should
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// exit the termination protocol after it's entered it.
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virtual bool should_exit_termination();
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HeapWord* finger() { return _finger; }
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bool has_aborted() { return _has_aborted; }
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void set_has_aborted() { _has_aborted = true; }
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void clear_has_aborted() { _has_aborted = false; }
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bool claimed() { return _claimed; }
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void set_oop_closure(OopClosure* oop_closure) {
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_oop_closure = oop_closure;
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}
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// It grays the object by marking it and, if necessary, pushing it
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// on the local queue
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void deal_with_reference(oop obj);
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// It scans an object and visits its children.
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void scan_object(oop obj) {
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assert(_nextMarkBitMap->isMarked((HeapWord*) obj), "invariant");
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if (_cm->verbose_high())
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gclog_or_tty->print_cr("[%d] we're scanning object "PTR_FORMAT,
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_task_id, (void*) obj);
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size_t obj_size = obj->size();
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_words_scanned += obj_size;
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obj->oop_iterate(_oop_closure);
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statsOnly( ++_objs_scanned );
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check_limits();
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}
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// It pushes an object on the local queue.
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void push(oop obj);
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// These two move entries to/from the global stack.
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void move_entries_to_global_stack();
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void get_entries_from_global_stack();
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// It pops and scans objects from the local queue. If partially is
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// true, then it stops when the queue size is of a given limit. If
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// partially is false, then it stops when the queue is empty.
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void drain_local_queue(bool partially);
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// It moves entries from the global stack to the local queue and
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// drains the local queue. If partially is true, then it stops when
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// both the global stack and the local queue reach a given size. If
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// partially if false, it tries to empty them totally.
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void drain_global_stack(bool partially);
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// It keeps picking SATB buffers and processing them until no SATB
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// buffers are available.
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void drain_satb_buffers();
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// It keeps popping regions from the region stack and processing
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// them until the region stack is empty.
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void drain_region_stack(BitMapClosure* closure);
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// moves the local finger to a new location
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inline void move_finger_to(HeapWord* new_finger) {
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assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
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_finger = new_finger;
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}
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// moves the region finger to a new location
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inline void move_region_finger_to(HeapWord* new_finger) {
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assert(new_finger < _cm->finger(), "invariant");
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_region_finger = new_finger;
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}
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CMTask(int task_num, ConcurrentMark *cm,
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CMTaskQueue* task_queue, CMTaskQueueSet* task_queues);
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// it prints statistics associated with this task
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void print_stats();
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#if _MARKING_STATS_
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void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; }
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#endif // _MARKING_STATS_
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};
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