提问：由于类没有找到，工作失败

[wangyp1230]

已经有一段时间了，每天晚上的工作都很好。但是，最近几天它推迟了几个小时，而且在第一步运行达一半时，就会有一个类没有找到的错误。这个错误我贴在了下面。它没有说具体是哪个类没有找到。
我们用的是Hadoop 1.0.3。非常感谢你们的帮助，谢谢。
Task attempt_201308210619_0001_r_000000_2 failed to report status for 600 seconds. Killing!
Task attempt_201308210619_0001_r_000000_2 failed to report status for 602 seconds. Killing!
attempt_201308210619_0001_r_000000_2: Exception in thread "IPC Client (47) connection to /127.0.0.1:60617 from job_201308210619_0001" java.lang.RuntimeException: readObject can't find class
attempt_201308210619_0001_r_000000_2: at org.apache.hadoop.io.ObjectWritable.readObject(ObjectWritable.java:185)
attempt_201308210619_0001_r_000000_2: at org.apache.hadoop.io.ObjectWritable.readFields(ObjectWritable.java:66)
attempt_201308210619_0001_r_000000_2: at org.apache.hadoop.ipc.Client$Connection.receiveResponse(Client.java:814)
attempt_201308210619_0001_r_000000_2: at org.apache.hadoop.ipc.Client$Connection.run(Client.java:749)
attempt_201308210619_0001_r_000000_2: Caused by: java.lang.ClassNotFoundException:
attempt_201308210619_0001_r_000000_2: at java.lang.Class.forName0(Native Method)
attempt_201308210619_0001_r_000000_2: at java.lang.Class.forName(Class.java:270)
attempt_201308210619_0001_r_000000_2: at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:820)
attempt_201308210619_0001_r_000000_2: at org.apache.hadoop.io.ObjectWritable.readObject(ObjectWritable.java:183)
attempt_201308210619_0001_r_000000_2: ... 3 more
Exception in thread "main" java.io.IOException: Job failed!
at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1320)