From 2dede35a180160e91d72a5194fc9b8f476f902a4 Mon Sep 17 00:00:00 2001
From: Aleksey Shipilev <shade@openjdk.org>
Date: Wed, 8 May 2019 14:27:14 +0200
Subject: [PATCH] 8223570: Shenandoah needs to acquire lock before
 CLDG::clear_claimed_marks

Reviewed-by: rkennke, tschatzl
---
 src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp b/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp
index 5ccdcb2e499..b8b12c8f2fb 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp
@@ -554,7 +554,10 @@ bool ShenandoahTraversalGC::check_and_handle_cancelled_gc(ShenandoahTaskTerminat
 }
 
 void ShenandoahTraversalGC::concurrent_traversal_collection() {
-  ClassLoaderDataGraph::clear_claimed_marks();
+  {
+    MutexLocker ml(ClassLoaderDataGraph_lock);
+    ClassLoaderDataGraph::clear_claimed_marks();
+  }
 
   ShenandoahGCPhase phase_work(ShenandoahPhaseTimings::conc_traversal);
   if (!_heap->cancelled_gc()) {