--- old/src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp	2018-06-11 15:58:43.278546970 +0200
+++ new/src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp	2018-06-11 15:58:43.066539684 +0200
@@ -2775,7 +2775,12 @@
       AbstractGangTask(name),
       _collector(collector),
       _n_workers(n_workers),
-      _par_state_string(StringTable::weak_storage()) {}
+      _par_state_string(StringTable::weak_storage()) {
+    StringTable::reset_dead_counter();
+  }
+  ~CMSParMarkTask() {
+    StringTable::finish_dead_counter();
+  }
   // Work method in support of parallel rescan ... of young gen spaces
   void do_young_space_rescan(OopsInGenClosure* cl,
                              ContiguousSpace* space,