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comparison src/share/vm/prims/jvmtiTagMap.cpp @ 3815:d425748f2203

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7043987: 3/3 JVMTI FollowReferences is slow Summary: VM_HeapWalkOperation::doit() should only reset mark bits when necessary. Reviewed-by: dsamersoff, ysr, dholmes, dcubed Contributed-by: ashok.srinivasa.murthy@oracle.com
author dcubed
date Thu, 23 Jun 2011 20:31:43 -0700
parents 167b70ff3abc
children 88dce6a60ac8
comparison
equal deleted inserted replaced
3814:1744e37e032b 3815:d425748f2203
1645 class ObjectMarker : AllStatic { 1645 class ObjectMarker : AllStatic {
1646 private: 1646 private:
1647 // saved headers 1647 // saved headers
1648 static GrowableArray<oop>* _saved_oop_stack; 1648 static GrowableArray<oop>* _saved_oop_stack;
1649 static GrowableArray<markOop>* _saved_mark_stack; 1649 static GrowableArray<markOop>* _saved_mark_stack;
1650 static bool _needs_reset; // do we need to reset mark bits?
1650 1651
1651 public: 1652 public:
1652 static void init(); // initialize 1653 static void init(); // initialize
1653 static void done(); // clean-up 1654 static void done(); // clean-up
1654 1655
1655 static inline void mark(oop o); // mark an object 1656 static inline void mark(oop o); // mark an object
1656 static inline bool visited(oop o); // check if object has been visited 1657 static inline bool visited(oop o); // check if object has been visited
1658
1659 static inline bool needs_reset() { return _needs_reset; }
1660 static inline void set_needs_reset(bool v) { _needs_reset = v; }
1657 }; 1661 };
1658 1662
1659 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL; 1663 GrowableArray<oop>* ObjectMarker::_saved_oop_stack = NULL;
1660 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL; 1664 GrowableArray<markOop>* ObjectMarker::_saved_mark_stack = NULL;
1665 bool ObjectMarker::_needs_reset = true; // need to reset mark bits by default
1661 1666
1662 // initialize ObjectMarker - prepares for object marking 1667 // initialize ObjectMarker - prepares for object marking
1663 void ObjectMarker::init() { 1668 void ObjectMarker::init() {
1664 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 1669 assert(Thread::current()->is_VM_thread(), "must be VMThread");
1665 1670
1678 // Object marking is done so restore object headers 1683 // Object marking is done so restore object headers
1679 void ObjectMarker::done() { 1684 void ObjectMarker::done() {
1680 // iterate over all objects and restore the mark bits to 1685 // iterate over all objects and restore the mark bits to
1681 // their initial value 1686 // their initial value
1682 RestoreMarksClosure blk; 1687 RestoreMarksClosure blk;
1683 Universe::heap()->object_iterate(&blk); 1688 if (needs_reset()) {
1689 Universe::heap()->object_iterate(&blk);
1690 } else {
1691 // We don't need to reset mark bits on this call, but reset the
1692 // flag to the default for the next call.
1693 set_needs_reset(true);
1694 }
1684 1695
1685 // When sharing is enabled we need to restore the headers of the objects 1696 // When sharing is enabled we need to restore the headers of the objects
1686 // in the readwrite space too. 1697 // in the readwrite space too.
1687 if (UseSharedSpaces) { 1698 if (UseSharedSpaces) {
1688 GenCollectedHeap* gch = GenCollectedHeap::heap(); 1699 GenCollectedHeap* gch = GenCollectedHeap::heap();
3233 3244
3234 assert(visit_stack()->is_empty(), "visit stack must be empty"); 3245 assert(visit_stack()->is_empty(), "visit stack must be empty");
3235 3246
3236 // the heap walk starts with an initial object or the heap roots 3247 // the heap walk starts with an initial object or the heap roots
3237 if (initial_object().is_null()) { 3248 if (initial_object().is_null()) {
3249 // If either collect_stack_roots() or collect_simple_roots()
3250 // returns false at this point, then there are no mark bits
3251 // to reset.
3252 ObjectMarker::set_needs_reset(false);
3253
3238 if (!collect_simple_roots()) return; 3254 if (!collect_simple_roots()) return;
3239 if (!collect_stack_roots()) return; 3255 if (!collect_stack_roots()) return;
3256
3257 // no early return so enable heap traversal to reset the mark bits
3258 ObjectMarker::set_needs_reset(true);
3240 } else { 3259 } else {
3241 visit_stack()->push(initial_object()()); 3260 visit_stack()->push(initial_object()());
3242 } 3261 }
3243 3262
3244 // object references required 3263 // object references required