[jira] Issue Comment Edited: (HADOOP-4664) Parallelize job initialization

["Devaraj Das (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-4664?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12681393#action_12681393 ] 

Devaraj Das edited comment on HADOOP-4664 at 3/12/09 9:59 AM:
--------------------------------------------------------------

I just committed this to the 0.20 branch and the trunk. Thanks Matei and Jothi!

      was (Author: devaraj):
    I just committed this to the 0.20 branch and the trunk.
  
> 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: hadoop-4664-v1.patch, hadoop-4664-v2.patch, hadoop-4664-v3.patch, hadoop-4664-v4.patch, 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.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.