[jira] [Resolved] (MAPREDUCE-497) TaskTracker.addDiagnostics(String file, int num, String tag) could exit early if num==0

["Allen Wittenauer (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAPREDUCE-497?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Allen Wittenauer resolved MAPREDUCE-497.
----------------------------------------

    Resolution: Incomplete

Closing this as stale.

> TaskTracker.addDiagnostics(String file, int num, String tag) could exit early if num==0
> ---------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-497
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-497
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>            Reporter: Steve Loughran
>            Priority: Minor
>
> When a TaskTracker job finishes,  taskFinished() is invoked. 
> as part of its work it
>  1. loads in a conf option (that is not in hadoop-default, incidentally) , mapred.debug.out.lines , default value -1;
>  2. calls addDiagnostics passing in that line count
> addDiagnostics either builds a string buffer of all the output, or creates a linear array of lines and runs adds them, shuffling them up if there are more lines than expected. 
> This is all unneeded if the number of lines to print == 0; the entire reading in of the output file can be skipped. This may speed up termination slightly on a run with a large output file and mapred.debug.out.lines ==0. 
> Note also that a circular buffer would handle the lines>0 problem without having to copy all the strings around.



--
This message was sent by Atlassian JIRA
(v6.2#6252)