hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2774) Add counters to show number of key/values that have been sorted and merged in the maps and reduces
Date Wed, 19 Nov 2008 03:50:46 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2774?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12648903#action_12648903
] 

Chris Douglas commented on HADOOP-2774:
---------------------------------------

bq. It is difficult to have a testcase for this issue since the number of spilled records
depend on a number of factors like the value of io.sort.mb, io.sort.factor, etc. Also, it
is not guaranteed that the number will not change when we make changes in the merge/sort algorithm
in the future.

This can- and should- have a unit test. While there are several, configurable parameters that
determine the number of spills, it can be calculated and verified. If there are changes to
the framework that invalidate the unit test, it can be updated or removed when that happens.

> Add counters to show number of key/values that have been sorted and merged in the maps
and reduces
> --------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-2774
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2774
>             Project: Hadoop Core
>          Issue Type: Bug
>            Reporter: Owen O'Malley
>            Assignee: Ravi Gummadi
>             Fix For: 0.20.0
>
>         Attachments: HADOOP-2774.patch, HADOOP-2774.patch
>
>
> For each *pass* of the sort and merge, I would like a count of the number of records.
So for example, if the map output 100 records and they were sorted once, the counter would
be 100. If it spilled twice and was merged together, it would be 200. Clearly in a multi-level
merge, it may not be a multiple of the number of map output records. This would let the users
easily see if they have values like io.sort.mb or io.sort.factor set too low.

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


Mime
View raw message