hadoop-mapreduce-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Siddharth Seth (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MAPREDUCE-6197) Cache MapOutputLocations in ShuffleHandler
Date Tue, 16 Dec 2014 01:11:47 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-6197?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Siddharth Seth updated MAPREDUCE-6197:
--------------------------------------
    Affects Version/s: 2.6.0

> Cache MapOutputLocations in ShuffleHandler
> ------------------------------------------
>
>                 Key: MAPREDUCE-6197
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6197
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: 2.6.0
>            Reporter: Siddharth Seth
>
> ShuffleHandler currently seems to create a map of mapId - mapInfo (file.out / index information)
when it receives a message.
> This should be caching map info across requests, so that the a scan of all directories
is not required for each reducer fetching from the same map.
> Also, the scan for each map output / index file is performed twice per mapId within a
request. In populateHeaders - once in the call to getMapOutputInfo, and then directly in the
method.
> For an invocation where we do end up with more than 1000 (default) mapIds in a single
call, and don't cache them in the map - the path constructed for such entries will be invalid.
This is highly unlikely to be the case though, until there's proper caching.
> {code}
> MapOutputInfo info = mapOutputInfoMap.get(mapId);
>           if (info == null) {
>             info = getMapOutputInfo(outputBasePathStr, mapId, reduceId, user);
>           }
> {code}



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message