src/share/vm/gc/shared/collectedHeap.hpp

rev 13349 : imported patch deflate.patch

*** 47,56 ****
--- 47,57 ----
  class MetaspaceSummary;
  class Thread;
  class ThreadClosure;
  class VirtualSpaceSummary;
  class nmethod;
+ class WorkGang;
  
  class GCMessage : public FormatBuffer<1024> {
   public:
    bool is_before;
  
*** 598,607 ****
--- 599,633 ----
    virtual void verify(VerifyOption option) = 0;
  
    // Accumulate additional statistics from GCLABs.
    virtual void accumulate_statistics_all_gclabs();
  
+   // Return true if GC supports per-thread monitor deflation.
+   // In this case, idle monitors will not get deflated when entering
+   // a safepoint, but instead will get deflated when the GC
+   // calls into Thread::oops_do() or Thread::possibly_parallel_oops_do().
+   // This allows for better parallelization and cache behaviour.
+   //
+   // NOTICE that monitor deflation requires the mark words to be intact,
+   // which means that this can only be supported by GCs that don't stow
+   // away the mark word in order to temporarily store a forwarding pointer
+   // to it.
+   virtual bool supports_per_thread_monitor_deflation() const {
+     return false;
+   }
+ 
+   // This is called by ObjectSynchronizer::deflate_idle_monitors() when
+   // the above supports_per_thread_monitor_deflation() returns false,
+   // or on special non-GC cleanup safepoints (even if the above returns true).
+   // It gives the GC a chance to deflate idle monitors using its GC worker
+   // threads, and thus support parallelization of monitor deflation.
+   // The default implementation simply deflates idle monitors single-threaded,
+   // using the calling (VM) thread.
+   virtual void deflate_idle_monitors_all_threads();
+ 
+   void parallel_deflate_idle_monitors(WorkGang* workers);
+ 
    // Non product verification and debugging.
  #ifndef PRODUCT
    // Support for PromotionFailureALot.  Return true if it's time to cause a
    // promotion failure.  The no-argument version uses
    // this->_promotion_failure_alot_count as the counter.