正文之前
今天很气愤！！想要学点东西，但是老是被环境所限制。Hadoop这个见鬼的环境，我只是运行单机模式，结果就是都不成功。好不容易磕磕盼盼的终于把啥缺的东西都找出来了结果最后还是失败了。暂时我真的不想去看失败记录，因为快要睡了明天再说吧。另外我这里有《Hadoop 权威指南》第三版的翻译版本（华东师范大学翻译）。我今天吃完晚饭去书店逛的时候又看到了第四版的盗版书。所以见猎心喜之下买了回来。如果有哪位同志想要哪一页，可以让我帮忙拍一下，当然全本就免了，自己看电子书吧！！
正文
今天遇到的一个很大的问题是。Java我没法儿找到安装路径。这简直是巨坑？？配置$HADOOP_HOME/etc/hadoop/hadoop-env.sh这个见鬼的玩意的时候，找不到JAVA_HOME?？？岂不是要gg，这也太惨了？？？所以我左找右找，终于给我逮到了！下面是博客来源，感谢大神！！
另外，我用另外一台云服务器亲自验证了我前面介绍的那一篇老外写的很新版的Hadoop教程。具体请看下列链接：
【Hadoop学起来】分布式Hadoop的搭建（Ubuntu 17.04）
另外就是下载的资源更新啦，自己看评论！！
第一步：whereis java
[root@Hadoop Master java]# whereis java
java: /usr/bin/java /etc/java /usr/lib/java /usr/share/java /usr/share/man/man1/java.1.gz
第二步：ls -lrt /usr/bin/java
[root@Hadoop Master java]# ls -lrt /usr/bin/java
lrwxrwxrwx. 1 root root 22 Nov 2 23:38 /usr/bin/java -> /etc/alternatives/java
第三步：ls -lrt /etc/alternatives/java
[root@Hadoop Master java]# ls -lrt /etc/alternatives/java
lrwxrwxrwx. 1 root root 46 Nov 2 23:38 /etc/alternatives/java -> /usr/lib/jvm/java
第四步：设置环境变量
vi 此文件/etc/profile
在profile文件末尾加入：，
export JAVA_HOME=/usr/lib/jvm/java
（上面这一行也加到标题里面那个地址的文件中去，记得把原来的删掉）
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
（我记得这一些好像也~/.bashrc这个文件里面，同样的也要生效一下）
第五步：使生效 ：source /etc/profile
综合上面这些步骤就已经完成了更新JAVA的环境变量这一过程~~
从上方图片可以看出来。当我运行gps命令的时候。是完全可以显示出Hadoop需要的那些组件的。理论上来说应该可以完成那个问题。但是我也不知道为什么，总是有bug!!!
root@VM-161-78-ubuntu:/home/ubuntu/hadoop/hadoop# bin/yarn jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.8.2.jar pi 16 1000
上面所要求的问题
Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF-8
Picked up _JAVA_OPTIONS: -Xmx512M
Number of Maps = 16
Samples per Map = 1000
18/01/10 00:41:47 WARN hdfs.DataStreamer: DataStreamer Exception
org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user/root/QuasiMonteCarlo_1515516105834_522663899/in/part0 could only be replicated to 0 nodes instead of minReplication (=1). There are 0 datanode(s) running and no node(s) are excluded in this operation.
at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1728)
at org.apache.hadoop.hdfs.server.namenode.FSDirWriteFileOp.chooseTargetForNewBlock(FSDirWriteFileOp.java:265)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2515)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:828)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:507)
at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:447)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:989)
at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:847)
at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:790)
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:1836)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2486)
at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1483)
at org.apache.hadoop.ipc.Client.call(Client.java:1429)
at org.apache.hadoop.ipc.Client.call(Client.java:1339)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
at com.sun.proxy.$Proxy10.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:440)
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.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:409)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:163)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:155)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:346)
at com.sun.proxy.$Proxy11.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.DataStreamer.locateFollowingBlock(DataStreamer.java:1809)
at org.apache.hadoop.hdfs.DataStreamer.nextBlockOutputStream(DataStreamer.java:1609)
at org.apache.hadoop.hdfs.DataStreamer.run(DataStreamer.java:704)
org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user/root/QuasiMonteCarlo_1515516105834_522663899/in/part0 could only be replicated to 0 nodes instead of minReplication (=1). There are 0 datanode(s) running and no node(s) are excluded in this operation.
at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1728)
at org.apache.hadoop.hdfs.server.namenode.FSDirWriteFileOp.chooseTargetForNewBlock(FSDirWriteFileOp.java:265)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2515)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:828)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:507)
at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:447)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:989)
at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:847)
at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:790)
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:1836)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2486)
at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1483)
at org.apache.hadoop.ipc.Client.call(Client.java:1429)
at org.apache.hadoop.ipc.Client.call(Client.java:1339)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
at com.sun.proxy.$Proxy10.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:440)
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.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:409)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:163)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:155)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:346)
at com.sun.proxy.$Proxy11.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.DataStreamer.locateFollowingBlock(DataStreamer.java:1809)
at org.apache.hadoop.hdfs.DataStreamer.nextBlockOutputStream(DataStreamer.java:1609)
at org.apache.hadoop.hdfs.DataStreamer.run(DataStreamer.java:704)
上面是我的运行记录。我是真的不想去看哪个地方出问题了。明天继续看我的书吧，这些糟心的问题留到以后解决。现在对这个东西的理解还不够，很难看出什么问题来！
诸位再看一下我另外一台云服务器上的相同操作。这台服务器是海外的，所以当初在官网下载镜像的时候简直快到不可思议。但是后来各种幺蛾子，甚至最近我发现他的NameNode会经常自己关闭，YARN这小畜生也是一样的德行！！
正文之后
不说了！有人催我睡觉了。这几天看看Hadoop吧。毕设毕竟要做这方面的东西。所以估计会很漫长的战线。开个系列。立个Flag咯~溜了溜了
