lost task trackers -- jobs hang
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Key: HADOOP-1874
URL: https://issues.apache.org/jira/browse/HADOOP-1874
Project: Hadoop
Issue Type: Bug
Components: mapred
Affects Versions: 0.15.0
Reporter: Christian Kunz
Priority: Blocker
This happens on a 1400 node cluster using a recent nightly build patched with
HADOOP-1763 (that fixes a previous 'lost task tracker' issue) running a
c++-pipes job with 4200 maps and 2800 reduces. The task trackers start to get
lost in high numbers at the end of job completion.
Similar non-pipes job do not show the same problem, but is unclear whether it
is related to c++-pipes. It could also be dfs overload when reduce tasks close
and validate all newly created dfs files. I see dfs client rpc timeout
exception. But this alone does not explain the escalation in losing task
trackers.
I also noticed that the job tracker becomes rather unresponsive with rpc
timeout and call queue overflow exceptions. Job Tracker is running with 60
handlers.
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