8376410: G1: Task queue statistics not reset properly on mark abort

Reviewed-by: shade, iwalulya

src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

@@ -639,8 +639,7 @@ void G1ConcurrentMark::reset_marking_for_restart() {
   _finger = _heap.start();
 
   for (uint i = 0; i < _max_num_tasks; ++i) {
-    G1CMTaskQueue* queue = _task_queues->queue(i);
-    queue->set_empty();
+    _tasks[i]->reset_for_restart();
   }
 }
 
@@ -1943,11 +1942,7 @@ bool G1ConcurrentMark::concurrent_cycle_abort() {
     return false;
   }
 
-  // Empty mark stack
   reset_marking_for_restart();
-  for (uint i = 0; i < _max_num_tasks; ++i) {
-    _tasks[i]->clear_region_fields();
-  }
 
   abort_marking_threads();
 
@@ -2118,6 +2113,13 @@ void G1CMTask::reset(G1CMBitMap* mark_bitmap) {
   _mark_stats_cache.reset();
 }
 
+void G1CMTask::reset_for_restart() {
+  clear_region_fields();
+  _task_queue->set_empty();
+  TASKQUEUE_STATS_ONLY(_partial_array_splitter.stats()->reset());
+  TASKQUEUE_STATS_ONLY(_task_queue->stats.reset());
+}
+
 void G1CMTask::register_partial_array_splitter() {
 
   ::new (&_partial_array_splitter) PartialArraySplitter(_cm->partial_array_state_manager(),

src/hotspot/share/gc/g1/g1ConcurrentMark.hpp

@@ -844,8 +844,10 @@ private:
   // Apply the closure to the given range of elements in the objArray.
   inline void process_array_chunk(objArrayOop obj, size_t start, size_t end);
 public:
-  // Resets the task; should be called right at the beginning of a marking phase.
+  // Resets the task completely for a new marking; should be called right at the beginning of a marking phase.
   void reset(G1CMBitMap* mark_bitmap);
+  // Minimal reset of the task, making it ready for continuing to mark.
+  void reset_for_restart();
   // Register/unregister Partial Array Splitter Allocator with the PartialArrayStateManager.
   // This allows us to discard memory arenas used for partial object array states at the end
   // of a concurrent mark cycle.