Hi, Our prod cluster met some issues recently, All map tasks finished successfully, but reduce task hanged.
but It's not happened on all TaskTrackers, only sometimes. we used mapred-1.0.4 There is "0.0% reduce > copy >" forever until kill task manually. reduce logs on the TaskTracker: hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:13:57 INFO mapred.TaskTracker: JVM with ID: jvm_201312201200_34795_r_-365330778 given task: attempt_201312201200_34795_r_000000_0 hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:04 INFO mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce > copy > hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:08 INFO mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce > copy > hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:14 INFO mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce > copy > hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:17 INFO mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce > copy > hadoop-hadoop-tasktracker-10-200-91-186.out:14/01/03 06:14:23 INFO mapred.TaskTracker: attempt_201312201200_34795_r_000000_0 0.0% reduce > copy >
