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diff src/share/vm/gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp @ 452:00b023ae2d78

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6722113: CMS: Incorrect overflow handling during precleaning of Reference lists Summary: When we encounter marking stack overflow during precleaning of Reference lists, we were using the overflow list mechanism, which can cause problems on account of mutating the mark word of the header because of conflicts with mutator accesses and updates of that field. Instead we should use the usual mechanism for overflow handling in concurrent phases, namely dirtying of the card on which the overflowed object lies. Since precleaning effectively does a form of discovered list processing, albeit with discovery enabled, we needed to adjust some code to be correct in the face of interleaved processing and discovery. Reviewed-by: apetrusenko, jcoomes
author ysr
date Thu, 20 Nov 2008 12:27:41 -0800
parents b5489bb705c9
children 05f89f00a864 148e5441d916
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp	Wed Nov 19 14:20:51 2008 -0800
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/cmsOopClosures.hpp	Thu Nov 20 12:27:41 2008 -0800
@@ -325,24 +325,30 @@
 // For objects in CMS generation, this closure marks
 // given objects (transitively) as being reachable/live.
 // This is currently used during the (weak) reference object
-// processing phase of the CMS final checkpoint step.
+// processing phase of the CMS final checkpoint step, as
+// well as during the concurrent precleaning of the discovered
+// reference lists.
 class CMSKeepAliveClosure: public OopClosure {
  private:
   CMSCollector* _collector;
   const MemRegion _span;
   CMSMarkStack* _mark_stack;
   CMSBitMap*    _bit_map;
+  bool          _concurrent_precleaning;
  protected:
   DO_OOP_WORK_DEFN
  public:
   CMSKeepAliveClosure(CMSCollector* collector, MemRegion span,
-                      CMSBitMap* bit_map, CMSMarkStack* mark_stack):
+                      CMSBitMap* bit_map, CMSMarkStack* mark_stack,
+                      bool cpc):
     _collector(collector),
     _span(span),
     _bit_map(bit_map),
-    _mark_stack(mark_stack) {
+    _mark_stack(mark_stack),
+    _concurrent_precleaning(cpc) {
     assert(!_span.is_empty(), "Empty span could spell trouble");
   }
+  bool    concurrent_precleaning() const { return _concurrent_precleaning; }
   virtual void do_oop(oop* p);
   virtual void do_oop(narrowOop* p);
   inline void do_oop_nv(oop* p)       { CMSKeepAliveClosure::do_oop_work(p); }