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diff src/share/vm/gc_implementation/g1/g1MarkSweep.cpp @ 3772:6747fd0512e0

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7004681: G1: Extend marking verification to Full GCs Summary: Perform a heap verification after the first phase of G1's full GC using objects' mark words to determine liveness. The third parameter of the heap verification routines, which was used in G1 to determine which marking bitmap to use in liveness calculations, has been changed from a boolean to an enum with values defined for using the mark word, and the 'prev' and 'next' bitmaps. Reviewed-by: tonyp, ysr
author johnc
date Tue, 14 Jun 2011 11:01:10 -0700
parents 1216415d8e35
children 4dfb2df418f2
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -84,11 +84,6 @@
 
   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
 
-  if (VerifyDuringGC) {
-      G1CollectedHeap* g1h = G1CollectedHeap::heap();
-      g1h->checkConcurrentMark();
-  }
-
   mark_sweep_phase2();
 
   // Don't add any more derived pointers during phase3
@@ -179,6 +174,29 @@
 
   assert(GenMarkSweep::_marking_stack.is_empty(),
          "stack should be empty by now");
+
+  if (VerifyDuringGC) {
+    HandleMark hm;  // handle scope
+    COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
+    gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
+    Universe::heap()->prepare_for_verify();
+    // Note: we can verify only the heap here. When an object is
+    // marked, the previous value of the mark word (including
+    // identity hash values, ages, etc) is preserved, and the mark
+    // word is set to markOop::marked_value - effectively removing
+    // any hash values from the mark word. These hash values are
+    // used when verifying the dictionaries and so removing them
+    // from the mark word can make verification of the dictionaries
+    // fail. At the end of the GC, the orginal mark word values
+    // (including hash values) are restored to the appropriate
+    // objects.
+    Universe::heap()->verify(/* allow dirty */ true,
+                             /* silent      */ false,
+                             /* option      */ VerifyOption_G1UseMarkWord);
+
+    G1CollectedHeap* g1h = G1CollectedHeap::heap();
+    gclog_or_tty->print_cr("]");
+  }
 }
 
 class G1PrepareCompactClosure: public HeapRegionClosure {