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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-2790) TaskInProgress.hasSpeculativeTask is very inefficient
Date Fri, 29 Feb 2008 01:05:51 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-2790?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Owen O'Malley updated HADOOP-2790:
----------------------------------

    Status: Patch Available  (was: Open)

Before the patch, findNewTask took 60s, with the patch it took 53s in my test case using Yourkit.

> 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.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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