diff -r 7aa1b3d6ff8f -r 68134337dbf8 src/hotspot/share/jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.cpp
--- a/src/hotspot/share/jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.cpp	Sun Aug 25 13:27:54 2019 +0200
+++ b/src/hotspot/share/jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.cpp	Sun Aug 25 15:13:16 2019 +0200
@@ -31,6 +31,8 @@
 // The regular epoch shift happens only during a safepoint.
 // The fence is there only for the emergency dump case which happens outside of safepoint.
 bool JfrTraceIdEpoch::_epoch_state = false;
+bool volatile JfrTraceIdEpoch::_klass_tagged_in_epoch = false;
+
 void JfrTraceIdEpoch::shift_epoch() {
   _epoch_state = !_epoch_state;
   if (!SafepointSynchronize::is_at_safepoint()) {