我一直在寻找解决办法，但一无所获。也许这里有人遇到了这样的问题，有了一些想法。
基本上，我和hadoop一起工作，试图完成一些mapreduce任务。一个主节点和两个从节点。配置似乎还可以，因为我可以用ssh从每个节点连接到每个节点。我已经准备好了 /etc/hosts 以及hadoop的配置，例如： mapred-site.xml , hdfs-site.xml .
任务执行后，一切似乎都好了。没有错误或警告，但当我 grep WARN 在日志文件中，有一些条目让我担心。
在 tasktracker-master.log 我发现：

2013-06-03 14:14:47,525 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:15:00,680 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.
2013-06-03 14:17:44,352 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:17:59,182 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.
2013-06-03 14:23:49,419 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:23:55,156 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.
2013-06-03 14:27:40,619 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:27:46,382 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.
2013-06-03 14:34:15,498 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:34:22,103 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.
2013-06-03 14:36:38,551 WARN org.apache.hadoop.mapred.TaskTracker: Unknown job job_201306031434_0002 being deleted.
2013-06-03 14:37:17,724 WARN org.apache.hadoop.mapred.TaskTracker: Unknown job job_201306031434_0003 being deleted.
2013-06-03 14:59:42,395 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:59:48,158 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.`

同样的事情也发生在 slave1/slave2 :

tasktracker-slave1.log:
2013-06-03 14:59:34,439 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:59:45,954 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.
2013-06-03 15:01:29,380 WARN org.apache.hadoop.mapred.TaskTracker: Unknown job job_201306031459_0001 being deleted.
2013-06-03 15:03:14,848 WARN org.apache.hadoop.mapred.TaskTracker: Unknown job job_201306031459_0003 being deleted.

tasktracker-slave2.log:
2013-06-03 14:59:37,642 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2013-06-03 14:59:45,805 WARN org.apache.hadoop.mapred.TaskTracker: TaskTracker's totalMemoryAllottedForTasks is -1. TaskMemoryManager is disabled.
2013-06-03 15:02:29,489 WARN org.apache.hadoop.mapred.TaskTracker: Unknown job job_201306031459_0002 being deleted.

有人见过这些警告，知道它们是什么意思吗？
还有一件事，我怎样才能知道任务是否真的在所有假定的节点上执行 master, slave1, slave2 ? 这些警告意味着 slave1/slave2 你不工作吗？
我希望我已经清楚地描述了我的问题。谢谢你的帮助。