HADOOP-10214. Fix multithreaded correctness warnings in ActiveStandbyElector (Liang Xie via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1556735 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -212,6 +212,9 @@ Release 2.4.0 - UNRELEASED
     HADOOP-10207. TestUserGroupInformation#testLogin is flaky (jxiang via
     cmccabe)
 
+    HADOOP-10214. Fix multithreaded correctness warnings in ActiveStandbyElector
+    (Liang Xie via kasha)
+
 Release 2.3.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ha/ActiveStandbyElector.java

@@ -768,7 +768,7 @@ public class ActiveStandbyElector implements StatCallback, StringCallback {
   }
 
   @InterfaceAudience.Private
-  public void terminateConnection() {
+  public synchronized void terminateConnection() {
     if (zkClient == null) {
       return;
     }