YARN-11838: YARN ConcurrentModificationException When Refreshing Node Attributes

Author: shameersss1

hadoop-common-project/hadoop-common/src/main/conf/core-site.xml

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="UTF-8"?>
+x<?xml version="1.0" encoding="UTF-8"?>
 <?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
 <!--
   Licensed under the Apache License, Version 2.0 (the "License");

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/nodelabels/NodeAttributesManagerImpl.java

@@ -745,7 +745,14 @@ public void refreshNodeAttributesToScheduler(NodeId nodeId) {
 
     // Notify RM
     if (rmContext != null && rmContext.getDispatcher() != null) {
-      LOG.info("Updated NodeAttribute event to RM:" + newNodeToAttributesMap);
+      // iterating newNodeToAttributesMap will access host.attributes
+      // which might be modified by other threads.
+      readLock.lock();
+      try {
+        LOG.info("Updated NodeAttribute event to RM:" + newNodeToAttributesMap);
+      } finally {
+        readLock.unlock();
+      }
       rmContext.getDispatcher().getEventHandler().handle(
           new NodeAttributesUpdateSchedulerEvent(newNodeToAttributesMap));
     }