我试图在这里给出的Hadoop中运行示例程序
当我尝试运行它时,我得到一个org.apache.hadoop.mapred.FileAlreadyExistsException
emil@psycho-O:~/project/hadoop-0.20.2$ bin/hadoop jar jar_files/wordcount.jar org.myorg.WordCount jar_files/wordcount/input jar_files/wordcount/output
11/02/06 14:54:23 INFO jvm.JvmMetrics: Initializing JVM Metrics with processName=JobTracker, sessionId=
11/02/06 14:54:23 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
Exception in thread "main" org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory file:/home/emil/project/hadoop-0.20.2/jar_files/wordcount/input already exists
at org.apache.hadoop.mapred.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:111)
at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:772)
at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:730)
at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1249)
at org.myorg.WordCount.main(WordCount.java:55)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
emil@psycho-O:~/project/hadoop-0.20.2$
它来自/home/emil/project/hadoop-0.20.2/jar_files/wordcount/input,我将输入文件file01和file02.当我用Google搜索时,我发现这样做是为了防止重新执行相同的任务.但在我的情况下,它的输入文件导致异常.我的命令有什么问题,因为我没有看到任何有关wordcount问题的错误相同的帖子.我是java的新手.
这可能是什么原因？
我试图在我的系统中设置apache hadoop.在过程页面中,它说"编辑文件conf/hadoop-env.sh以至少将JAVA_HOME定义为Java安装的根目录."
设置"JAVA_HOME"和"java分区的根"实际意味着什么.root是否意味着java加载的位置(即"哪个java"命令的输出)？
我正在使用Fedora 12
我有一个自己制作的jar文件"Tsp.jar".这个相同的jar文件在hadoop的单节点集群设置中执行良好.然而,当我在包含2台机器,笔记本电脑和台式机的集群上运行它时,当地图功能达到50%时,它会给我一个例外.这是输出
`hadoop@psycho-O:/usr/local/hadoop$ bin/hadoop jar Tsp.jar clust-Tsp_ip1 clust_Tsp_op4
11/04/27 16:13:06 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
11/04/27 16:13:06 WARN mapred.JobClient: No job jar file set. User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
11/04/27 16:13:06 INFO mapred.FileInputFormat: Total input paths to process : 1
11/04/27 16:13:06 INFO mapred.JobClient: Running job: job_201104271608_0001
11/04/27 16:13:07 INFO mapred.JobClient: map 0% reduce 0%
11/04/27 16:13:17 INFO mapred.JobClient: map 50% reduce 0%
11/04/27 16:13:20 INFO …