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Posted to common-dev@hadoop.apache.org by "Hemanth Yamijala (JIRA)" <ji...@apache.org> on 2009/03/02 16:42:56 UTC
[jira] Assigned: (HADOOP-4664) Parallelize job initialization
[ https://issues.apache.org/jira/browse/HADOOP-4664?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Hemanth Yamijala reassigned HADOOP-4664:
----------------------------------------
Assignee: Jothi Padmanabhan (was: Matei Zaharia)
> 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: Jothi Padmanabhan
> 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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