From 6493c9a6b8aa5f55a60f1c1700f6da215c226d55 Mon Sep 17 00:00:00 2001
From: Lu <877856611@qq.com>
Date: Thu, 18 Jul 2019 19:12:39 +0800
Subject: [PATCH] =?UTF-8?q?double=20check=20=E5=8F=98=E9=87=8F=E9=9C=80?=
 =?UTF-8?q?=E8=A6=81volatile=E4=BF=AE=E9=A5=B0?=
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---
 .../escheduler/common/queue/TaskQueueZkImpl.java   | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/escheduler-common/src/main/java/cn/escheduler/common/queue/TaskQueueZkImpl.java b/escheduler-common/src/main/java/cn/escheduler/common/queue/TaskQueueZkImpl.java
index de37b5ffce..2febb6ee13 100644
--- a/escheduler-common/src/main/java/cn/escheduler/common/queue/TaskQueueZkImpl.java
+++ b/escheduler-common/src/main/java/cn/escheduler/common/queue/TaskQueueZkImpl.java
@@ -17,20 +17,26 @@
 package cn.escheduler.common.queue;
 
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+import java.util.TreeSet;
+
 import cn.escheduler.common.Constants;
 import cn.escheduler.common.utils.Bytes;
 import cn.escheduler.common.utils.IpUtils;
 import cn.escheduler.common.utils.OSUtils;
 import cn.escheduler.common.zk.AbstractZKClient;
-import org.apache.commons.lang3.StringUtils;
 import org.apache.curator.framework.CuratorFramework;
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.data.Stat;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.*;
-
 /**
  * A singleton of a task queue implemented with zookeeper
  * tasks queue implemention
@@ -39,7 +45,7 @@ public class TaskQueueZkImpl extends AbstractZKClient implements ITaskQueue {
 
     private static final Logger logger = LoggerFactory.getLogger(TaskQueueZkImpl.class);
 
-    private static TaskQueueZkImpl instance;
+    private static volatile TaskQueueZkImpl instance;
 
     private TaskQueueZkImpl(){
         init();