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diff src/share/vm/gc_implementation/g1/heapRegion.cpp @ 1886:72a161e62cc4

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6991377: G1: race between concurrent refinement and humongous object allocation Summary: There is a race between the concurrent refinement threads and the humongous object allocation that can cause the concurrent refinement threads to corrupt the part of the BOT that it is being initialized by the humongous object allocation operation. The solution is to do the humongous object allocation in careful steps to ensure that the concurrent refinement threads always have a consistent view over the BOT, region contents, and top. The fix includes some very minor tidying up in sparsePRT. Reviewed-by: jcoomes, johnc, ysr
author tonyp
date Sat, 16 Oct 2010 17:12:19 -0400
parents bb847e31b836
children 2d26b0046e0d f95d63e2154a
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/heapRegion.cpp	Mon Oct 18 15:01:41 2010 -0700
+++ b/src/share/vm/gc_implementation/g1/heapRegion.cpp	Sat Oct 16 17:12:19 2010 -0400
@@ -377,10 +377,26 @@
 }
 // </PREDICTION>
 
-void HeapRegion::set_startsHumongous() {
+void HeapRegion::set_startsHumongous(HeapWord* new_end) {
+  assert(end() == _orig_end,
+         "Should be normal before the humongous object allocation");
+  assert(top() == bottom(), "should be empty");
+
   _humongous_type = StartsHumongous;
   _humongous_start_region = this;
-  assert(end() == _orig_end, "Should be normal before alloc.");
+
+  set_end(new_end);
+  _offsets.set_for_starts_humongous(new_end);
+}
+
+void HeapRegion::set_continuesHumongous(HeapRegion* start) {
+  assert(end() == _orig_end,
+         "Should be normal before the humongous object allocation");
+  assert(top() == bottom(), "should be empty");
+  assert(start->startsHumongous(), "pre-condition");
+
+  _humongous_type = ContinuesHumongous;
+  _humongous_start_region = start;
 }
 
 bool HeapRegion::claimHeapRegion(jint claimValue) {
@@ -500,23 +516,6 @@
   return blk.result();
 }
 
-void HeapRegion::set_continuesHumongous(HeapRegion* start) {
-  // The order is important here.
-  start->add_continuingHumongousRegion(this);
-  _humongous_type = ContinuesHumongous;
-  _humongous_start_region = start;
-}
-
-void HeapRegion::add_continuingHumongousRegion(HeapRegion* cont) {
-  // Must join the blocks of the current H region seq with the block of the
-  // added region.
-  offsets()->join_blocks(bottom(), cont->bottom());
-  arrayOop obj = (arrayOop)(bottom());
-  obj->set_length((int) (obj->length() + cont->capacity()/jintSize));
-  set_end(cont->end());
-  set_top(cont->end());
-}
-
 void HeapRegion::save_marks() {
   set_saved_mark();
 }