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

@@ -1087,10 +1087,12 @@
   log_debug(gc, verify)("RemSet");
   rem_set()->verify();
 }
 
 void GenCollectedHeap::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);
 }