From 656b0148bfd851386190a549f69e5e374c087050 Mon Sep 17 00:00:00 2001
From: chengxiangwang <chengxiangwang@cmss.chinamobile.com>
Date: Thu, 1 Nov 2018 23:22:15 +0800
Subject: [PATCH] use putIfAbsent instead of put

---
 .../java/org/apache/rocketmq/common/stats/StatsItemSet.java | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/common/src/main/java/org/apache/rocketmq/common/stats/StatsItemSet.java b/common/src/main/java/org/apache/rocketmq/common/stats/StatsItemSet.java
index 9a0caaa1..b3686516 100644
--- a/common/src/main/java/org/apache/rocketmq/common/stats/StatsItemSet.java
+++ b/common/src/main/java/org/apache/rocketmq/common/stats/StatsItemSet.java
@@ -162,10 +162,10 @@ public class StatsItemSet {
         StatsItem statsItem = this.statsItemTable.get(statsKey);
         if (null == statsItem) {
             statsItem = new StatsItem(this.statsName, statsKey, this.scheduledExecutorService, this.log);
-            StatsItem prev = this.statsItemTable.put(statsKey, statsItem);
-
-            if (null == prev) {
+            StatsItem prev = this.statsItemTable.putIfAbsent(statsKey, statsItem);
 
+            if (null != prev) {
+                statsItem = prev;
                 // statsItem.init();
             }
         }
-- 
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