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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2790) TaskInProgress.hasSpeculativeTask is very inefficient
Date Sat, 01 Mar 2008 09:09:51 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2790?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12574087#action_12574087
] 

Devaraj Das commented on HADOOP-2790:
-------------------------------------

Owen, could you please submit one patch for 0.16 branch. This patch doesn't apply cleanly
there.

> TaskInProgress.hasSpeculativeTask is very inefficient
> -----------------------------------------------------
>
>                 Key: HADOOP-2790
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2790
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>            Reporter: Owen O'Malley
>            Assignee: Owen O'Malley
>             Fix For: 0.16.1
>
>         Attachments: 2790-2.patch, 2790.patch
>
>
> Each call to JobInProgress.findNewTask can call TaskInProgress.hasSpeculativeTask once
per a task. Each call to hasSpeculativeTask calls System.getCurrentTimeMillis, which can result
in hundreds of thousands of calls to getCurrentTimeMillis. Additionally, it calls TaskInProgress.isOnlyCommitPending,
which calls .values() on the map from task id to host name and iterates through them to see
if any of the tasks are in commit pending. It would be better to have a commit pending boolean
flag in the TaskInProgress. It also looks like there are other opportunities here, but those
jumped out at me. We should also look at this method in the profiler.

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