8234020: Remove FullGCCount_lock

Reviewed-by: kbarrett

src/hotspot/share/gc/shared/genCollectedHeap.cpp

@@ -254,28 +254,9 @@ size_t GenCollectedHeap::max_capacity() const {
 // Update the _full_collections_completed counter
 // at the end of a stop-world full GC.
 unsigned int GenCollectedHeap::update_full_collections_completed() {
-  MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
   assert(_full_collections_completed <= _total_full_collections,
          "Can't complete more collections than were started");
   _full_collections_completed = _total_full_collections;
-  ml.notify_all();
-  return _full_collections_completed;
-}
-
-// Update the _full_collections_completed counter, as appropriate,
-// at the end of a concurrent GC cycle. Note the conditional update
-// below to allow this method to be called by a concurrent collector
-// without synchronizing in any manner with the VM thread (which
-// may already have initiated a STW full collection "concurrently").
-unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
-  MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
-  assert((_full_collections_completed <= _total_full_collections) &&
-         (count <= _total_full_collections),
-         "Can't complete more collections than were started");
-  if (count > _full_collections_completed) {
-    _full_collections_completed = count;
-    ml.notify_all();
-  }
   return _full_collections_completed;
 }
 

src/hotspot/share/gc/shared/genCollectedHeap.hpp

@@ -281,8 +281,6 @@ class GenCollectedHeap : public CollectedHeap {
 
   // Update above counter, as appropriate, at the end of a stop-world GC cycle
   unsigned int update_full_collections_completed();
-  // Update above counter, as appropriate, at the end of a concurrent GC cycle
-  unsigned int update_full_collections_completed(unsigned int count);
 
   // Update the gc statistics for each generation.
   void update_gc_stats(Generation* current_generation, bool full) {

src/hotspot/share/runtime/mutexLocker.cpp

@@ -72,7 +72,6 @@ Mutex*   NonJavaThreadsList_lock      = NULL;
 Mutex*   NonJavaThreadsListSync_lock  = NULL;
 Monitor* CGC_lock                     = NULL;
 Monitor* STS_lock                     = NULL;
-Monitor* FullGCCount_lock             = NULL;
 Monitor* G1OldGCCount_lock            = NULL;
 Mutex*   Shared_DirtyCardQ_lock       = NULL;
 Mutex*   G1DetachedRefinementStats_lock = NULL;
@@ -212,7 +211,6 @@ void mutex_init() {
   def(CGC_lock                     , PaddedMonitor, special,     true,  _safepoint_check_never);      // coordinate between fore- and background GC
   def(STS_lock                     , PaddedMonitor, leaf,        true,  _safepoint_check_never);
 
-  def(FullGCCount_lock             , PaddedMonitor, leaf,        true,  _safepoint_check_never);      // in support of ExplicitGCInvokesConcurrent
   if (UseG1GC) {
     def(G1OldGCCount_lock          , PaddedMonitor, leaf,        true,  _safepoint_check_always);
 

src/hotspot/share/runtime/mutexLocker.hpp

@@ -66,7 +66,6 @@ extern Mutex*   NonJavaThreadsListSync_lock;     // a lock for NonJavaThreads li
 extern Monitor* CGC_lock;                        // used for coordination between
                                                  // fore- & background GC threads.
 extern Monitor* STS_lock;                        // used for joining/leaving SuspendibleThreadSet.
-extern Monitor* FullGCCount_lock;                // in support of "concurrent" full gc
 extern Monitor* G1OldGCCount_lock;               // in support of "concurrent" full gc
 extern Mutex*   Shared_DirtyCardQ_lock;          // Lock protecting dirty card
                                                  // queue shared by