From 011989665e9ec6061d91ac5c935a52d7edf85e13 Mon Sep 17 00:00:00 2001
From: Andrew Purtell <apurtell@apache.org>
Date: Fri, 25 May 2018 10:25:29 -0700
Subject: [PATCH] HBASE-20597 Serialize access to a shared reference to
 ZooKeeperWatcher in HBaseReplicationEndpoint

---
 .../hbase/replication/HBaseReplicationEndpoint.java    | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/HBaseReplicationEndpoint.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/HBaseReplicationEndpoint.java
index 6485e4afb50..6d3e70e3351 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/HBaseReplicationEndpoint.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/replication/HBaseReplicationEndpoint.java
@@ -43,19 +43,17 @@ import org.apache.zookeeper.KeeperException.SessionExpiredException;
  * target cluster is an HBase cluster.
  */
 @InterfaceAudience.Private
-@edu.umd.cs.findbugs.annotations.SuppressWarnings(value="MT_CORRECTNESS",
-  justification="Thinks zkw needs to be synchronized access but should be fine as is.")
 public abstract class HBaseReplicationEndpoint extends BaseReplicationEndpoint
   implements Abortable {
 
   private static final Log LOG = LogFactory.getLog(HBaseReplicationEndpoint.class);
 
-  private ZooKeeperWatcher zkw = null; // FindBugs: MT_CORRECTNESS
+  private ZooKeeperWatcher zkw = null;
 
   private List<ServerName> regionServers = new ArrayList<ServerName>(0);
   private long lastRegionServerUpdate;
 
-  protected void disconnect() {
+  protected synchronized void disconnect() {
     if (zkw != null) {
       zkw.close();
     }
@@ -113,7 +111,7 @@ public abstract class HBaseReplicationEndpoint extends BaseReplicationEndpoint
    * Get the ZK connection to this peer
    * @return zk connection
    */
-  protected ZooKeeperWatcher getZkw() {
+  protected synchronized ZooKeeperWatcher getZkw() {
     return zkw;
   }
 
@@ -121,7 +119,7 @@ public abstract class HBaseReplicationEndpoint extends BaseReplicationEndpoint
    * Closes the current ZKW (if not null) and creates a new one
    * @throws IOException If anything goes wrong connecting
    */
-  void reloadZkWatcher() throws IOException {
+  synchronized void reloadZkWatcher() throws IOException {
     if (zkw != null) zkw.close();
     zkw = new ZooKeeperWatcher(ctx.getConfiguration(),
         "connection to cluster: " + ctx.getPeerId(), this);