Hadoop yarn nodemanager重启之后，就在resourcemanager上多一个重复节点

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如题。比方说我目前在hadoop yarn resourcemanager节点上的web界面看到的可用节点是这样的:

一共3个nodemanager。当我把rtdstest2这个节点的nodemanager服务重启之后，刷新一下发现多了一个重复的rtdstest2:

如果MR任务分配到了之前已经停掉的实例上，也会hang住走不下去。想问问看这是怎么回事？应该如何避免？

最后贴出我的几个配置，请帮我看看是不是哪里配置的不对(所有节点配置相同)？

core-site.xml:

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<configuration>
 <property>
  <name>fs.defaultFS</name>
  <value>hdfs://rtdstest</value>
 </property>
 <property>
  <name>hadoop.proxyuser.mapred.groups</name>
  <value>*</value>
 </property>
 <property>
  <name>hadoop.proxyuser.mapred.hosts</name>
  <value>*</value>
 </property>
</configuration>

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<configuration>
 <property>
  <name>mapreduce.framework.name</name>
  <value>yarn</value>
 </property>
 <property>
  <name>mapreduce.jobhistory.address</name>
  <value>172.16.250.10:10020</value>
 </property>
 <property>
  <name>mapreduce.jobhistory.webapp.address</name>
  <value>172.16.250.10:19888</value>
 </property>
 <property>
  <name>yarn.app.mapreduce.am.staging-dir</name>
  <value>/user</value>
 </property>
</configuration>

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<configuration>
 <property>
  <name>yarn.resourcemanager.hostname</name>
  <value>rtdstest</value>
 </property>
 <property>
  <name>yarn.nodemanager.aux-services</name>
  <value>mapreduce_shuffle</value>
 </property>
 <property>
  <name>yarn.nodemanager.aux-services.mapreduce_shuffle.class</name>
  <value>org.apache.hadoop.mapred.ShuffleHandler</value>
 </property>
 <property>
  <name>yarn.log-aggregation-enable</name>
  <value>true</value>
 </property>
 <property>
  <description>List of directories to store localized files in.</description>
  <name>yarn.nodemanager.local-dirs</name>
  <value>file:///var/lib/hadoop-yarn/cache/${user.name}/nm-local-dir</value>
 </property>
 <property>
  <description>Where to store container logs.</description>
  <name>yarn.nodemanager.log-dirs</name>
  <value>file:///var/log/hadoop-yarn/containers</value>
 </property>
 <property>
  <description>Where to aggregate logs to.</description>
  <name>yarn.nodemanager.remote-app-log-dir</name>
  <value>/var/log/hadoop-yarn/apps</value>
 </property>
 <property>
  <description>Classpath for typical applications.</description>
  <name>yarn.application.classpath</name>
  <value>
   $HADOOP_CONF_DIR,
   $HADOOP_COMMON_HOME/*,$HADOOP_COMMON_HOME/lib/*,
   $HADOOP_HDFS_HOME/*,$HADOOP_HDFS_HOME/lib/*,
   $HADOOP_MAPRED_HOME/*,$HADOOP_MAPRED_HOME/lib/*,
   $HADOOP_YARN_HOME/*,$HADOOP_YARN_HOME/lib/*
  </value>
 </property>
</configuration>