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diff src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp @ 453:c96030fff130

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6684579: SoftReference processing can be made more efficient Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not. Reviewed-by: jmasa
author ysr
date Thu, 20 Nov 2008 16:56:09 -0800
parents 00b023ae2d78
children 27a80744a83b
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Thu Nov 20 12:27:41 2008 -0800
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Thu Nov 20 16:56:09 2008 -0800
@@ -1961,6 +1961,7 @@
 
   ref_processor()->set_enqueuing_is_done(false);
   ref_processor()->enable_discovery();
+  ref_processor()->snap_policy(clear_all_soft_refs);
   // If an asynchronous collection finishes, the _modUnionTable is
   // all clear.  If we are assuming the collection from an asynchronous
   // collection, clear the _modUnionTable.
@@ -2384,6 +2385,9 @@
     Universe::verify(true);
   }
 
+  // Snapshot the soft reference policy to be used in this collection cycle.
+  ref_processor()->snap_policy(clear_all_soft_refs);
+
   bool init_mark_was_synchronous = false; // until proven otherwise
   while (_collectorState != Idling) {
     if (TraceCMSState) {
@@ -4591,11 +4595,11 @@
     if (!dirtyRegion.is_empty()) {
       assert(numDirtyCards > 0, "consistency check");
       HeapWord* stop_point = NULL;
+      stopTimer();
+      CMSTokenSyncWithLocks ts(true, gen->freelistLock(),
+                               bitMapLock());
+      startTimer();
       {
-        stopTimer();
-        CMSTokenSyncWithLocks ts(true, gen->freelistLock(),
-                                 bitMapLock());
-        startTimer();
         verify_work_stacks_empty();
         verify_overflow_empty();
         sample_eden();
@@ -4612,10 +4616,6 @@
         assert((CMSPermGenPrecleaningEnabled && (gen == _permGen)) ||
                (_collectorState == AbortablePreclean && should_abort_preclean()),
                "Unparsable objects should only be in perm gen.");
-
-        stopTimer();
-        CMSTokenSyncWithLocks ts(true, bitMapLock());
-        startTimer();
         _modUnionTable.mark_range(MemRegion(stop_point, dirtyRegion.end()));
         if (should_abort_preclean()) {
           break; // out of preclean loop
@@ -5678,23 +5678,14 @@
 
   ResourceMark rm;
   HandleMark   hm;
-  ReferencePolicy* soft_ref_policy;
-
-  assert(!ref_processor()->enqueuing_is_done(), "Enqueuing should not be complete");
-  // Process weak references.
-  if (clear_all_soft_refs) {
-    soft_ref_policy = new AlwaysClearPolicy();
-  } else {
-#ifdef COMPILER2
-    soft_ref_policy = new LRUMaxHeapPolicy();
-#else
-    soft_ref_policy = new LRUCurrentHeapPolicy();
-#endif // COMPILER2
-  }
-  verify_work_stacks_empty();
 
   ReferenceProcessor* rp = ref_processor();
   assert(rp->span().equals(_span), "Spans should be equal");
+  assert(!rp->enqueuing_is_done(), "Enqueuing should not be complete");
+  // Process weak references.
+  rp->snap_policy(clear_all_soft_refs);
+  verify_work_stacks_empty();
+
   CMSKeepAliveClosure cmsKeepAliveClosure(this, _span, &_markBitMap,
                                           &_markStack, false /* !preclean */);
   CMSDrainMarkingStackClosure cmsDrainMarkingStackClosure(this,
@@ -5704,14 +5695,12 @@
     TraceTime t("weak refs processing", PrintGCDetails, false, gclog_or_tty);
     if (rp->processing_is_mt()) {
       CMSRefProcTaskExecutor task_executor(*this);
-      rp->process_discovered_references(soft_ref_policy,
-                                        &_is_alive_closure,
+      rp->process_discovered_references(&_is_alive_closure,
                                         &cmsKeepAliveClosure,
                                         &cmsDrainMarkingStackClosure,
                                         &task_executor);
     } else {
-      rp->process_discovered_references(soft_ref_policy,
-                                        &_is_alive_closure,
+      rp->process_discovered_references(&_is_alive_closure,
                                         &cmsKeepAliveClosure,
                                         &cmsDrainMarkingStackClosure,
                                         NULL);
@@ -6166,8 +6155,8 @@
 #endif
 
 size_t CMSCollector::block_size_using_printezis_bits(HeapWord* addr) const {
-  assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1),
-         "missing Printezis mark?");
+   assert(_markBitMap.isMarked(addr) && _markBitMap.isMarked(addr + 1),
+          "missing Printezis mark?");
   HeapWord* nextOneAddr = _markBitMap.getNextMarkedWordAddress(addr + 2);
   size_t size = pointer_delta(nextOneAddr + 1, addr);
   assert(size == CompactibleFreeListSpace::adjustObjectSize(size),