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

*** 21,30 ****
--- 21,31 ----
   * 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"
*** 2600,2620 ****
    // Unload Klasses, String, Symbols, Code Cache, etc.
    {
      G1RemarkGCTraceTime trace("Unloading", G1Log::finer());
  
      if (ClassUnloadingWithConcurrentMark) {
        bool purged_classes;
  
        {
          G1RemarkGCTraceTime trace("System Dictionary Unloading", G1Log::finest());
!         purged_classes = SystemDictionary::do_unloading(&g1_is_alive);
        }
  
        {
          G1RemarkGCTraceTime trace("Parallel Unloading", G1Log::finest());
          weakRefsWorkParallelPart(&g1_is_alive, purged_classes);
        }
      }
  
      if (G1StringDedup::is_enabled()) {
        G1RemarkGCTraceTime trace("String Deduplication Unlink", G1Log::finest());
        G1StringDedup::unlink(&g1_is_alive);
--- 2601,2631 ----
    // 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, 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);