共计 3252 个字符，预计需要花费 9 分钟才能阅读完成。
一个 Hadoop 难以查找的错误
This script is Deprecated. Instead use start-dfs.sh and start-yarn.sh
Starting namenodes on [Master132.Hadoop]
Master132.Hadoop: starting namenode, logging to /usr/hadoop/logs/hadoop-hadoop-namenode-Master132.Hadoop.out
Slave110.Hadoop: /usr/hadoop/sbin/hadoop-daemon.sh: line 69: [: .out: integer expression expected
Slave110.Hadoop: starting datanode, logging to /usr/hadoop/logs/hadoop-hadoop-datanode-Slave110.Hadoop
Slave131.Hadoop: starting datanode, logging to /usr/hadoop/logs/hadoop-hadoop-datanode-Slave131.Hadoop.out
Slave141.Hadoop: starting datanode, logging to /usr/hadoop/logs/hadoop-hadoop-datanode-Slave141.Hadoop.out
Slave110.Hadoop: Exception in thread “main“ Java.lang.NoClassDefFoundError: /log
Slave110.Hadoop: Caused by: java.lang.ClassNotFoundException: .log
Slave110.Hadoop: at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
Slave110.Hadoop: at java.security.AccessController.doPrivileged(Native Method)
Slave110.Hadoop: at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
Slave110.Hadoop: at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
Slave110.Hadoop: at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
Slave110.Hadoop: at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Slave110.Hadoop: Could not find the main class: .log. Program will exit.
Starting secondary namenodes [Master132.Hadoop]
Master132.Hadoop: starting secondarynamenode, logging to /usr/hadoop/logs/hadoop-hadoop-secondarynamenode-Master132.Hadoop.out
starting yarn daemons
starting resourcemanager, logging to /usr/hadoop/logs/yarn-hadoop-resourcemanager-Master132.Hadoop.out
Slave110.Hadoop: /usr/hadoop/sbin/yarn-daemon.sh: line 72: [: .out: integer expression expected
Slave110.Hadoop: starting nodemanager, logging to /usr/hadoop/logs/yarn-hadoop-nodemanager-Slave110.Hadoop
Slave131.Hadoop: starting nodemanager, logging to /usr/hadoop/logs/yarn-hadoop-nodemanager-Slave131.Hadoop.out
Slave141.Hadoop: starting nodemanager, logging to /usr/hadoop/logs/yarn-hadoop-nodemanager-Slave141.Hadoop.out
Slave110.Hadoop: Exception in thread “main“ java.lang.NoClassDefFoundError: /log
Slave110.Hadoop: Caused by: java.lang.ClassNotFoundException: .log
Slave110.Hadoop: at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
Slave110.Hadoop: at java.security.AccessController.doPrivileged(Native Method)
Slave110.Hadoop: at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
Slave110.Hadoop: at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
Slave110.Hadoop: at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
Slave110.Hadoop: at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Slave110.Hadoop: Could not find the main class: .log. Program will exit.
周末，原本搭建好的 Hadoop 集群在启动中突然报出以上的错误！一个节点不好用了！经过了各种查找，还是没有解决。
今天终于查到原因了！datenode 节点 Slave110.Hadoop 的主机名后面不知道什么时候添加了一个空格！删除就好了！崩溃
相关阅读 ：
Ubuntu 13.04 上搭建 Hadoop 环境 http://www.linuxidc.com/Linux/2013-06/86106.htm
Ubuntu 12.10 +Hadoop 1.2.1 版本集群配置 http://www.linuxidc.com/Linux/2013-09/90600.htm
Ubuntu 上搭建 Hadoop 环境（单机模式 + 伪分布模式）http://www.linuxidc.com/Linux/2013-01/77681.htm
Ubuntu 下 Hadoop 环境的配置 http://www.linuxidc.com/Linux/2012-11/74539.htm
单机版搭建 Hadoop 环境图文教程详解 http://www.linuxidc.com/Linux/2012-02/53927.htm
搭建 Hadoop 环境（在 Winodws 环境下用虚拟机虚拟两个 Ubuntu 系统进行搭建）http://www.linuxidc.com/Linux/2011-12/48894.htm
更多 Hadoop 相关信息见 Hadoop 专题页面 http://www.linuxidc.com/topicnews.aspx?tid=13
