After some jobs have finished, Reducer will run new job's reduce tasks
sequentially and not in parallel (mapred.JobTracker: Serious problem. While
updating status, cannot find taskid...)
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Key: HADOOP-5367
URL: https://issues.apache.org/jira/browse/HADOOP-5367
Project: Hadoop Core
Issue Type: Bug
Affects Versions: 0.19.1
Environment: State: RUNNING
Started: Fri Feb 27 17:00:07 CET 2009
Version: 0.19.1, r745977
Compiled: Fri Feb 20 00:16:34 UTC 2009 by ndaley
Reporter: Thibaut
Priority: Critical
Hi,
After I while, my cluster will only run the reduce tasks sequentially (each
reducer running on the same node), the other nodes stay empty. The map phase
however will run the jobs on all the nodes. This happens in my cluster after
about 160 successfully completed jobs. (Some jobs have reducer set to 0!).
As possible solution I have to restart the mapreduce service.
I didn't notice this behaviour in version 0.19.0. I can't use version 0.19.0
because of the multipleoutput bug when setting reducers to 0.
Anoter site node which might be related. I also tried running the jobs with
speculative execution set to on. My cluster would always hold back one reducer
and only run it (in multiple instances) after the first of the other 6 reducers
had finished, instead of launching all of them at the same time.
Below is a short extract from related logfile. It's full of these kind of
entries.
09/02/28 12:48:07 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0051_r_000006_1
09/02/28 12:48:08 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0041_r_000002_1
09/02/28 12:48:08 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0083_r_000006_1
09/02/28 12:48:08 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0041_r_000005_1
09/02/28 12:48:10 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0105_r_000006_1
09/02/28 12:48:10 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0102_r_000006_1
09/02/28 12:48:12 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0051_r_000006_1
09/02/28 12:48:13 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0041_r_000002_1
09/02/28 12:48:13 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0083_r_000006_1
09/02/28 12:48:13 INFO mapred.JobTracker: Serious problem. While updating
status, cannot find taskid attempt_200902271700_0041_r_000005_1
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