src/share/vm/gc_implementation/g1/concurrentMark.cpp

rev 6875 : 8056240: Investigate increased GC remark time after class unloading changes in CRM Fuse
Reviewed-by: mgerdin, coleenp, bdelsart

@@ -21,10 +21,11 @@
  * questions.
  *
  */
 
 #include "precompiled.hpp"
+#include "classfile/metadataOnStackMark.hpp"
 #include "classfile/symbolTable.hpp"
 #include "code/codeCache.hpp"
 #include "gc_implementation/g1/concurrentMark.inline.hpp"
 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

@@ -2600,21 +2601,31 @@
   // Unload Klasses, String, Symbols, Code Cache, etc.
   {
     G1RemarkGCTraceTime trace("Unloading", G1Log::finer());
 
     if (ClassUnloadingWithConcurrentMark) {
+      // Cleaning of klasses depends on correct information from MetadataMarkOnStack. The CodeCache::mark_on_stack
+      // part is too slow to be done serially, so it is handled during the weakRefsWorkParallelPart phase.
+      // Defer the cleaning until we have complete on_stack data.
+      MetadataOnStackMark md_on_stack(false /* Don't visit the code cache at this point */);
+
       bool purged_classes;
 
       {
         G1RemarkGCTraceTime trace("System Dictionary Unloading", G1Log::finest());
-        purged_classes = SystemDictionary::do_unloading(&g1_is_alive);
+        purged_classes = SystemDictionary::do_unloading(&g1_is_alive, false /* Defer klass cleaning */);
       }
 
       {
         G1RemarkGCTraceTime trace("Parallel Unloading", G1Log::finest());
         weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
       }
+
+      {
+        G1RemarkGCTraceTime trace("Deallocate Metadata", G1Log::finest());
+        ClassLoaderDataGraph::free_deallocate_lists();
+      }
     }
 
     if (G1StringDedup::is_enabled()) {
       G1RemarkGCTraceTime trace("String Deduplication Unlink", G1Log::finest());
       G1StringDedup::unlink(&g1_is_alive);