BlogJava-jinfeng_wang-随笔分类-hadoophttp://www.blogjava.net/jinfeng_wang/category/49848.htmlG-G-S,D-D-U!zh-cnSun, 23 Oct 2011 15:34:21 GMTSun, 23 Oct 2011 15:34:21 GMT60运行 第一MapReduce程序遇到的问题。http://www.blogjava.net/jinfeng_wang/archive/2011/10/22/361807.htmljinfeng_wangjinfeng_wangSat, 22 Oct 2011 15:09:00 GMThttp://www.blogjava.net/jinfeng_wang/archive/2011/10/22/361807.htmlhttp://www.blogjava.net/jinfeng_wang/comments/361807.htmlhttp://www.blogjava.net/jinfeng_wang/archive/2011/10/22/361807.html#Feedback0http://www.blogjava.net/jinfeng_wang/comments/commentRss/361807.htmlhttp://www.blogjava.net/jinfeng_wang/services/trackbacks/361807.htmlhttp://hadoop.apache.org/mapreduce/docs/r0.21.0/mapred_tutorial.html


经验总结：
1）必须将相关的Class文件（包括Map，Reduce）打包成Jar文件
2）export HADOOP_CLASSPATH=./
3)  不要将Jar文件和Class文件混淆在一起，放在一个目录， 例如目录结构如下：
    否则执行 hadoop jar test.jar   NewMaxTemperature /input /output 的时候， 会出现 下面的错误，
    参考: http://groups.google.com/group/hadoopors/browse_thread/thread/b011ef93af5633ae/8227267657518bbb?#8227267657518bbb 
2011-10-22 22:44:12,062 INFO org.apache.hadoop.mapred.TaskInProgress: Error from attempt_201110222208_0014_m_000001_3 on tracker_ad:localhost/127.0.0.1:2401: java.lang.RuntimeException: java.lang.ClassNotFoundException: NewMaxTemperature$NewMaxTemperatureMapper
 at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1128)
 at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:167)
 at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:612)
 at org.apache.hadoop.mapred.MapTask.run(MapTask.java:328)
 at org.apache.hadoop.mapred.Child$4.run(Child.java:217)
 at java.security.AccessController.doPrivileged(Native Method)
 at javax.security.auth.Subject.doAs(Subject.java:415)
 at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:742)


jinfeng_wang 2011-10-22 23:09 发表评论
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