src/share/vm/runtime/synchronizer.cpp

rev 13002 : 8180175: ObjectSynchronizer only needs to iterate in-use monitors
Summary: When using -XX:+MonitorInUseLists, then only iterate in-use monitors.
Reviewed-by: zgu,dholmes

*** 962,971 ****
--- 962,982 ----
    return block;
  }
  
  
  void ObjectSynchronizer::oops_do(OopClosure* f) {
+   if (MonitorInUseLists) {
+     // When using thread local monitor lists, we only scan the
+     // global used list here (for moribund threads), and
+     // the thread-local monitors in Thread::oops_do().
+     global_used_oops_do(f);
+   } else {
+     global_oops_do(f);
+   }
+ }
+ 
+ void ObjectSynchronizer::global_oops_do(OopClosure* f) {
    assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
    PaddedEnd<ObjectMonitor> * block =
      (PaddedEnd<ObjectMonitor> *)OrderAccess::load_ptr_acquire(&gBlockList);
    for (; block != NULL; block = (PaddedEnd<ObjectMonitor> *)next(block)) {
      assert(block->object() == CHAINMARKER, "must be a block header");
*** 976,985 ****
--- 987,1016 ----
        }
      }
    }
  }
  
+ void ObjectSynchronizer::global_used_oops_do(OopClosure* f) {
+   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+   list_oops_do(gOmInUseList, f);
+ }
+ 
+ void ObjectSynchronizer::thread_local_used_oops_do(Thread* thread, OopClosure* f) {
+   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+   list_oops_do(thread->omInUseList, f);
+ }
+ 
+ void ObjectSynchronizer::list_oops_do(ObjectMonitor* list, OopClosure* f) {
+   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+   ObjectMonitor* mid;
+   for (mid = list; mid != NULL; mid = mid->FreeNext) {
+     if (mid->object() != NULL) {
+       f->do_oop((oop*)mid->object_addr());
+     }
+   }
+ }
+ 
  
  // -----------------------------------------------------------------------------
  // ObjectMonitor Lifecycle
  // -----------------------
  // Inflation unlinks monitors from the global gFreeList and