--- old/src/hotspot/share/gc/z/zRootsIterator.cpp	2019-08-05 15:48:10.706742563 +0200
+++ new/src/hotspot/share/gc/z/zRootsIterator.cpp	2019-08-05 15:48:10.467734761 +0200
@@ -272,6 +272,7 @@
     _vm_handles(this),
     _class_loader_data_graph(this) {
   ZStatTimer timer(ZSubPhaseConcurrentRootsSetup);
+  ClassLoaderDataGraph::clear_claimed_marks(cld_claim);
 }
 
 ZConcurrentRootsIterator::~ZConcurrentRootsIterator() {