You are viewing a plain text version of this content. The canonical link for it is here.

Posted to common-dev@hadoop.apache.org by "Arun C Murthy (JIRA)" <ji...@apache.org> on 2008/08/14 00:14:46 UTC

[jira] Assigned: (HADOOP-3940) Reduce often attempts in memory merge with no work

     [ https://issues.apache.org/jira/browse/HADOOP-3940?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Arun C Murthy reassigned HADOOP-3940:
-------------------------------------

    Assignee: Chris Douglas

+1

> Reduce often attempts in memory merge with no work
> --------------------------------------------------
>
>                 Key: HADOOP-3940
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3940
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>            Reporter: Chris Douglas
>            Assignee: Chris Douglas
>            Priority: Minor
>         Attachments: 3940-0.patch, 3940-1.patch
>
>
> ReduceTask.ReduceCopier.ShuffleRamManager initializes numRequiredMapOutputs to 0, so one of the predicates in ShuffleRamManager::waitForDataToMerge, {{numPendingRequests < numRequiredMapOutputs}}, is false until the first map output is fetched and false again after the last map output is fetched. The InMemFSMergeThread thread will loop busily in this state.

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