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https://issues.apache.org/jira/browse/HADOOP-4664?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Hemanth Yamijala updated HADOOP-4664:
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Priority: Blocker (was: Major)
Fix Version/s: 0.20.0
As per discussion in HADOOP-5286, we are trying to change the M/R design to not
be affected by a single slow data node. So, marking this a blocker for Hadoop
0.20. Matei, if it is acceptable, Jothi has volunteered to take your patch
forward, incorporating comments from Tom. Do you have any objections to this ?
> Parallelize job initialization
> ------------------------------
>
> Key: HADOOP-4664
> URL: https://issues.apache.org/jira/browse/HADOOP-4664
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Reporter: Matei Zaharia
> Assignee: Matei Zaharia
> Priority: Blocker
> Fix For: 0.20.0
>
> Attachments: parallel-job-init-v1.patch
>
>
> The job init thread currently initializes one job at a time. However, this is
> a lengthy and partly IO-bound process because all of the job's block
> locations need to be resolved through the namenode and a map of them needs to
> be built. It can take tens of seconds. As a result, the cluster sometimes
> initializes jobs too slowly for full utilization to be achieved, if there are
> many small jobs queued up. It would be better to have a pool of threads that
> initialize multiple jobs in parallel. One thing to be careful of, however, is
> not causing deadlocks or holding locks for too long in these threads.
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