src/share/vm/gc/parallel/parallelScavengeHeap.cpp

@@ -549,10 +549,12 @@
   VirtualSpaceSummary heap_summary = create_heap_space_summary();
   return PSHeapSummary(heap_summary, used(), old_summary, old_space, young_summary, eden_space, from_space, to_space);
 }
 
 void ParallelScavengeHeap::print_on(outputStream* st) const {
+  assert_locked_or_safepoint(Heap_lock);
+
   young_gen()->print_on(st);
   old_gen()->print_on(st);
   MetaspaceAux::print_on(st);
 }