hadoop0.20.2：The temporary job-output directory doesn't exist!

java.io.IOException: The temporary job-output directory hdfs://localhost:9000/user/huojushou/weblog/log1_output/_temporary doesn't exist!

    at org.apache.hadoop.mapred.FileOutputCommitter.getWorkPath(FileOutputCommitter.java:204)

    at org.apache.hadoop.mapred.FileOutputFormat.getTaskOutputPath(FileOutputFormat.java:234)

    at org.apache.hadoop.mapred.TextOutputFormat.getRecordWriter(TextOutputFormat.java:119)

    at org.apache.hadoop.mapred.ReduceTask.runOldReducer(ReduceTask.java:433)

    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:411)

    at org.apache.hadoop.mapred.Child.main(Child.java:170)

14/04/07 20:54:56 INFO mapred.JobClient: Task Id : attempt_201404061820_0010_r_000001_0, Status : FAILED

 解决方法：关闭hadoop的safe模式 hadoop dfsadmin -safemode leave。

 原因：有可能是在执行mapreduce任务时强制退出，迫使namenode进入safe模式。