8055416: Several vm/gc/heap/summary "After GC" events emitted for the same GC ID

Reviewed-by: brutisso, ehelin

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -1877,6 +1877,7 @@ G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
   _old_marking_cycles_started(0),
   _old_marking_cycles_completed(0),
   _concurrent_cycle_started(false),
+  _heap_summary_sent(false),
   _in_cset_fast_test(),
   _dirty_cards_region_list(NULL),
   _worker_cset_start_region(NULL),
@@ -2447,13 +2448,24 @@ void G1CollectedHeap::register_concurrent_cycle_end() {
     _gc_timer_cm->register_gc_end();
     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
 
+    // Clear state variables to prepare for the next concurrent cycle.
     _concurrent_cycle_started = false;
+    _heap_summary_sent = false;
   }
 }
 
 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
   if (_concurrent_cycle_started) {
-    trace_heap_after_gc(_gc_tracer_cm);
+    // This function can be called when:
+    //  the cleanup pause is run
+    //  the concurrent cycle is aborted before the cleanup pause.
+    //  the concurrent cycle is aborted after the cleanup pause,
+    //   but before the concurrent cycle end has been registered.
+    // Make sure that we only send the heap information once.
+    if (!_heap_summary_sent) {
+      trace_heap_after_gc(_gc_tracer_cm);
+      _heap_summary_sent = true;
+    }
   }
 }
 

src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp

@@ -346,6 +346,7 @@ private:
   volatile unsigned int _old_marking_cycles_completed;
 
   bool _concurrent_cycle_started;
+  bool _heap_summary_sent;
 
   // This is a non-product method that is helpful for testing. It is
   // called at the end of a GC and artificially expands the heap by