hadoop 0.0.0.0/0.0.0.0:10020 connection refused

问题： hadoop2.2.0执行wordCount 出现如下错误

14/04/04 17:32:34 INFOmapred.ClientServiceDelegate: Application state is completed.FinalApplicationStatus=SUCCEEDED. Redirecting to job history server  14/04/04 17:32:35 INFO ipc.Client: Retryingconnect to server: 0.0.0.0/0.0.0.0:10020. Already tried 0 time(s); retry policyis RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1 SECONDS)  14/04/04 17:32:36 INFO ipc.Client: Retryingconnect to server: 0.0.0.0/0.0.0.0:10020. Already tried 1 time(s); retry policyis RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1 SECONDS)  ...  java.io.IOException:java.net.ConnectException: Call From master/192.168.182.100 to 0.0.0.0:10020failed on connection exception: java.net.ConnectException: Connection refused;For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused           atorg.apache.hadoop.mapred.ClientServiceDelegate.invoke(ClientServiceDelegate.java:334)           atorg.apache.hadoop.mapred.ClientServiceDelegate.getJobStatus(ClientServiceDelegate.java:419)           atorg.apache.hadoop.mapred.YARNRunner.getJobStatus(YARNRunner.java:532)           atorg.apache.hadoop.mapreduce.Job$1.run(Job.java:314)           atorg.apache.hadoop.mapreduce.Job$1.run(Job.java:311)           atjava.security.AccessController.doPrivileged(Native Method)           atjavax.security.auth.Subject.doAs(Subject.java:415)           atorg.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1548)           ...  

从错误信息中需要访问端口 10020 可以大概看出，DataNode 需要访问 MapReduce JobHistory Server，如果没有修改则用默认值：0.0.0.0:10020 。需要修改配置文件 mapred-site.xml  ：

 

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1. <property>  
2.    <name>mapreduce.jobhistory.address</name>  
3.    <!-- 配置实际的主机名和端口-->  
4.    <value>master:10020</value>  
5. </property>  

并且启动MapReduce JobHistory Server服务:

在namenode上执行命令:

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1. sbin/mr-jobhistory-daemon.sh start historyserver  

这样在，namenode上会启动JobHistoryServer服务，可以在historyserver的日志中查看运行情况