運行hadoop2 自帶的圓周率計算方法時，報錯，找了半天，原來是在配置hadoop臨時目錄時，沒有給權限，找到配置的hadoop臨時目錄文件夾，修改權限即可
Application application_1548242073562_0005 failed 2 times due to AM Container for appattempt_1548242073562_0005_000002 exited with exitCode: 1 Failing this attempt.Diagnostics: [2019-01-23 20:50:53.319]Exception from container-launch. Container id: container_1548242073562_0005_02_000001 Exit code: 1 [2019-01-23 20:50:53.321]Container exited with a non-zero exit code 1. Error file: prelaunch.err. Last 4096 bytes of prelaunch.err : Last 4096 bytes of stderr : log4j:WARN No appenders could be found for logger (org.apache.hadoop.mapreduce.v2.app.MRAppMaster). log4j:WARN Please initialize the log4j system properly.
計算少的時，比如1 1，不報錯，如果計算稍微大的數字，如10 10 就直接報下面的異常
19/01/24 10:20:32 INFO ipc.Client: Retrying connect to server: 0.0.0.0/0.0.0.0:10020. Already tried 9 time(s); retry policy is RetryUpToMaximumCountWithFixedSleep(maxRetries=10, sleepTime=1000 MILLISECONDS) java.io.IOException: java.net.ConnectException: Your endpoint configuration is wrong; For more details see: http://wiki.apache.org/hadoop/UnsetHostnameOrPort at org.apache.hadoop.mapred.ClientServiceDelegate.invoke(ClientServiceDelegate.java:344) at org.apache.hadoop.mapred.ClientServiceDelegate.getJobStatus(ClientServiceDelegate.java:429) at org.apache.hadoop.mapred.YARNRunner.getJobStatus(YARNRunner.java:804) at org.apache.hadoop.mapreduce.Job$1.run(Job.java:331) at org.apache.hadoop.mapreduce.Job$1.run(Job.java:328) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1893) at org.apache.hadoop.mapreduce.Job.updateStatus(Job.java:328) at org.apache.hadoop.mapreduce.Job.isSuccessful(Job.java:624) at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1603) at org.apache.hadoop.examples.QuasiMonteCarlo.estimatePi(QuasiMonteCarlo.java:307) at org.apache.hadoop.examples.QuasiMonteCarlo.run(QuasiMonteCarlo.java:360) at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76) at org.apache.hadoop.examples.QuasiMonteCarlo.main(QuasiMonteCarlo.java:368) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.util.ProgramDriver$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:244) at org.apache.hadoop.util.RunJar.main(RunJar.java:158) Caused by: java.net.ConnectException: Your endpoint configuration is wrong; For more details see: http://wiki.apache.org/hadoop/UnsetHostnameOrPort 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:423) at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:824) at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:750) at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1511) at org.apache.hadoop.ipc.Client.call(Client.java:1453) at org.apache.hadoop.ipc.Client.call(Client.java:1363) at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227) at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116) at com.sun.proxy.$Proxy15.getJobReport(Unknown Source) at org.apache.hadoop.mapreduce.v2.api.impl.pb.client.MRClientProtocolPBClientImpl.getJobReport(MRClientProtocolPBClientImpl.java:133) at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.mapred.ClientServiceDelegate.invoke(ClientServiceDelegate.java:325) ... 27 more Caused by: java.net.ConnectException: Connection refused at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717) at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206) at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:531) at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:690) at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:794) at org.apache.hadoop.ipc.Client$Connection.access$3600(Client.java:412) at org.apache.hadoop.ipc.Client.getConnection(Client.java:1568) at org.apache.hadoop.ipc.Client.call(Client.java:1399) ... 36 more
后來在這里找到了答案https://blog.csdn.net/zhouyan8603/article/details/47398245，，hadoop的datanode需要訪問namenode的jobhistory server,如果沒有修改，則默認為0.0.0.0:10020，則可以修改mapred-site.xml文件：
<property> <name>mapreduce.jobhistory.address</name> <!-- 配置實際的Master主機名和端口--> <value>0.0.0.0:10020</value> </property> <property> <name>mapreduce.jobhistory.webapp.address</name> <!-- 配置實際的Master主機名和端口--> <value>0.0.0.0:19888</value> </property>
然后啟動historyserver，再嘗試10 10 完成
$HADOOP_HOME/sbin/mr-jobhistory-daemon.sh start historyserver