问题：
在进行grep案例的时候，执行第一条hadoop命令，报错了，查找原因原来是hosts文件没有更改
java.net.UnknownHostException: hadoop101: hadoop101: 域名解析暂时失败 at java.net.InetAddress.getLocalHost(InetAddress.java:1505) at org.apache.hadoop.metrics.MetricsUtil.getHostName(MetricsUtil.java:95) at org.apache.hadoop.metrics.MetricsUtil.createRecord(MetricsUtil.java:84) at org.apache.hadoop.metrics.jvm.JvmMetrics.<init>(JvmMetrics.java:87) at org.apache.hadoop.metrics.jvm.JvmMetrics.init(JvmMetrics.java:78) at org.apache.hadoop.metrics.jvm.JvmMetrics.init(JvmMetrics.java:65) at org.apache.hadoop.mapred.LocalJobRunnerMetrics.<init>(LocalJobRunnerMetrics.java:40) at org.apache.hadoop.mapred.LocalJobRunner.<init>(LocalJobRunner.java:714) at org.apache.hadoop.mapred.LocalJobRunner.<init>(LocalJobRunner.java:707) at org.apache.hadoop.mapred.LocalClientProtocolProvider.create(LocalClientProtocolProvider.java:42) at org.apache.hadoop.mapreduce.Cluster.initialize(Cluster.java:95) at org.apache.hadoop.mapreduce.Cluster.<init>(Cluster.java:82) at org.apache.hadoop.mapreduce.Cluster.<init>(Cluster.java:75) at org.apache.hadoop.mapreduce.Job$9.run(Job.java:1260) at org.apache.hadoop.mapreduce.Job$9.run(Job.java:1256) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657) at org.apache.hadoop.mapreduce.Job.connect(Job.java:1255) at org.apache.hadoop.mapreduce.Job.submit(Job.java:1284) at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1308) at org.apache.hadoop.examples.Grep.run(Grep.java:78) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) at org.apache.hadoop.examples.Grep.main(Grep.java:103) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:71) at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144) at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:74) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.util.RunJar.run(RunJar.java:221) at org.apache.hadoop.util.RunJar.main(RunJar.java:136) Caused by: java.net.UnknownHostException: hadoop101: 域名解析暂时失败 at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method) at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928) at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323) at java.net.InetAddress.getLocalHost(InetAddress.java:1500) ... 36 more 19/05/09 20:23:42 INFO metrics.MetricsUtil: Unable to obtain hostName java.net.UnknownHostException: hadoop101: hadoop101: 域名解析暂时失败 at java.net.InetAddress.getLocalHost(InetAddress.java:1505) at org.apache.hadoop.metrics.MetricsUtil.getHostName(MetricsUtil.java:95) at org.apache.hadoop.metrics.MetricsUtil.createRecord(MetricsUtil.java:84) at org.apache.hadoop.mapred.LocalJobRunnerMetrics.<init>(LocalJobRunnerMetrics.java:44) at org.apache.hadoop.mapred.LocalJobRunner.<init>(LocalJobRunner.java:714) at org.apache.hadoop.mapred.LocalJobRunner.<init>(LocalJobRunner.java:707) at org.apache.hadoop.mapred.LocalClientProtocolProvider.create(LocalClientProtocolProvider.java:42) at org.apache.hadoop.mapreduce.Cluster.initialize(Cluster.java:95) at org.apache.hadoop.mapreduce.Cluster.<init>(Cluster.java:82) at org.apache.hadoop.mapreduce.Cluster.<init>(Cluster.java:75) at org.apache.hadoop.mapreduce.Job$9.run(Job.java:1260) at org.apache.hadoop.mapreduce.Job$9.run(Job.java:1256) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657) at org.apache.hadoop.mapreduce.Job.connect(Job.java:1255) at org.apache.hadoop.mapreduce.Job.submit(Job.java:1284) at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1308) at org.apache.hadoop.examples.Grep.run(Grep.java:78) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) at org.apache.hadoop.examples.Grep.main(Grep.java:103) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:71) at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144) at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:74) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.util.RunJar.run(RunJar.java:221) at org.apache.hadoop.util.RunJar.main(RunJar.java:136) Caused by: java.net.UnknownHostException: hadoop101: 域名解析暂时失败 at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method) at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928) at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323) at java.net.InetAddress.getLocalHost(InetAddress.java:1500) ... 33 more java.net.UnknownHostException: hadoop101: hadoop101: 域名解析暂时失败 at java.net.InetAddress.getLocalHost(InetAddress.java:1505) at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:146) at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1290) at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1287) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657) at org.apache.hadoop.mapreduce.Job.submit(Job.java:1287) at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1308) at org.apache.hadoop.examples.Grep.run(Grep.java:78) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70) at org.apache.hadoop.examples.Grep.main(Grep.java:103) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:71) at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144) at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:74) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.util.RunJar.run(RunJar.java:221) at org.apache.hadoop.util.RunJar.main(RunJar.java:136) Caused by: java.net.UnknownHostException: hadoop101: 域名解析暂时失败 at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method) at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928) at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323) at java.net.InetAddress.getLocalHost(InetAddress.java:1500) ... 24 more
解决办法:
vim /etc/hosts 192.168.1.101 hadoop101
