---

Hadoop任务运行中java.net.ConnectException: to 0.0.0.0:10020 failed

在执行Hive 语句的任务时，最近频繁的发生如下的报错：

java.io.IOException: java.net.ConnectException: Call From hadoop-001/192.168.1.101 to 0.0.0.0:10020 failed on connection exception: java.net.ConnectException: 拒绝连接; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused        at org.apache.hadoop.mapred.ClientServiceDelegate.invoke(ClientServiceDelegate.java:334)        at org.apache.hadoop.mapred.ClientServiceDelegate.getJobStatus(ClientServiceDelegate.java:419)        at org.apache.hadoop.mapred.YARNRunner.getJobStatus(YARNRunner.java:532)        at org.apache.hadoop.mapreduce.Cluster.getJob(Cluster.java:183)        at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:580)        at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:578)        at java.security.AccessController.doPrivileged(Native Method)        at javax.security.auth.Subject.doAs(Subject.java:415)        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1548)        at org.apache.hadoop.mapred.JobClient.getJobUsingCluster(JobClient.java:578)        at org.apache.hadoop.mapred.JobClient.getJob(JobClient.java:596)        at org.apache.hadoop.hive.ql.exec.mr.HadoopJobExecHelper.progress(HadoopJobExecHelper.java:288)        at org.apache.hadoop.hive.ql.exec.mr.HadoopJobExecHelper.progress(HadoopJobExecHelper.java:547)        at org.apache.hadoop.hive.ql.exec.mr.ExecDriver.execute(ExecDriver.java:426)        at org.apache.hadoop.hive.ql.exec.mr.MapRedTask.execute(MapRedTask.java:136)        at org.apache.hadoop.hive.ql.exec.Task.executeTask(Task.java:153)        at org.apache.hadoop.hive.ql.exec.TaskRunner.runSequential(TaskRunner.java:85)        at org.apache.hadoop.hive.ql.Driver.launchTask(Driver.java:1503)        at org.apache.hadoop.hive.ql.Driver.execute(Driver.java:1270)        at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:1088)        at org.apache.hadoop.hive.ql.Driver.run(Driver.java:911)        at org.apache.hadoop.hive.ql.Driver.run(Driver.java:901)        at org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:268)        at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:220)        at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:423)        at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:359)        at org.apache.hadoop.hive.cli.CliDriver.executeDriver(CliDriver.java:742)        at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:686)        at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:625)        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)        at java.lang.reflect.Method.invoke(Method.java:606)        at org.apache.hadoop.util.RunJar.main(RunJar.java:212)

报错信息提示，在访问端口 100020的时候出错，这表示DataNode 需要访问 MapReduce JobHistory Server，而默认值是： 0.0.0.0:10020 。

修改配置文件

找到{HADOOP_HOME}/etc/hadoop/mapred-site.xml配置文件 ,增加如下配置：

<property>    <name>mapreduce.jobhistory.address</name>    <!-- 配置实际的主机名和端口-->    <value>{namenode}:10020</value></property>

启动 JobHistory 服务

在namenode上执行命令

{hadoop_dir}/sbin/mr-jobhistory-daemon.sh start historyserver

之后就可以在 historyserver 的日志中，查看job的运行情况了。

错误处理

启动服务不久报了如下的错误：

2016-07-29 14:36:44,418 ERROR org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager: Error while trying to scan the directory hdfs://namenode:9000/tmp/hadoop-yarn/staging/history/done_intermediate/hadoopjava.io.IOException: com.google.protobuf.ServiceException: java.lang.OutOfMemoryError: Java heap space   ......Caused by: com.google.protobuf.ServiceException: java.lang.OutOfMemoryError: Java heap space        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:242)    ......2016-07-29 14:40:07,068 ERROR org.apache.hadoop.mapreduce.v2.hs.HistoryFileManager: Error while trying to scan the directory hdfs://namenode:9000/tmp/hadoop-yarn/staging/history/done_intermediate/hadoopjava.io.IOException: com.google.protobuf.ServiceException: java.lang.OutOfMemoryError: GC overhead limit exceeded

接着我修改了配置文件，增加heap 的大小
${HADOOP_DIR}/etc/hadoop/mapred-env.sh

export HADOOP_JOB_HISTORYSERVER_HEAPSIZE=2000

重新启动 JobHistory 服务，问题解决。

---

[1] hadoop 0.0.0.0/0.0.0.0:10020 connection refused
[2] hadoop运行mapreduce作业无法连接0.0.0.0/0.0.0.0:10020