Hadoop2.6.0运行自带WordCount报错

运行Hadoop自带的WordCount报错。

错误日志：

2015-04-07 21:27:01,842 INFO org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMAppImpl: Application
application_1428407210365_0007 failed 2 times due to Error launching appattempt_1428407210365_0007_000002. Got exception: java.net.ConnectException: Call From Master.Hadoop/192.168.1.1 to localhost:60387 failed on connection exception: java.net.ConnectException:
Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:791)
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:731)
at org.apache.hadoop.ipc.Client.call(Client.java:1472)
at org.apache.hadoop.ipc.Client.call(Client.java:1399)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
at com.sun.proxy.$Proxy32.startContainers(Unknown Source)
at org.apache.hadoop.yarn.api.impl.pb.client.ContainerManagementProtocolPBClientImpl.startContainers(ContainerManagementProtocolPBClientImpl.java:96)
at org.apache.hadoop.yarn.server.resourcemanager.amlauncher.AMLauncher.launch(AMLauncher.java:119)
at org.apache.hadoop.yarn.server.resourcemanager.amlauncher.AMLauncher.run(AMLauncher.java:254)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

Caused by: java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:716)
at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:530)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:494)
at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:607)
at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:705)
at org.apache.hadoop.ipc.Client$Connection.access$2800(Client.java:368)
at org.apache.hadoop.ipc.Client.getConnection(Client.java:1521)
at org.apache.hadoop.ipc.Client.call(Client.java:1438)
... 9 more

解决办法：

HDFS在输出的时候需要新建输出文件

在core-site.xml中的配置项：需要配置fs.defaultFS和fs.default.name两个参数，参数值完全一样，这样Hadoop才能在HDFS系统中新建文件，不然，Hadoop无法新建输出结果文件，就会报错。