mapred.local.dir temp dir. space allocation limited by smallest area

• Key: HADOOP-9
• Type: Bug
• Status: Closed
• Resolution: Fixed
• Priority: Minor
• Assignee: Ari Rabkin
• Reporter: Paul Baclace
• Fix Version/s: 0.19.0

Description

When mapred.local.dir is used to specify multiple temp dir. areas, space allocation limited by smallest area because the temp dir. selection algorithm is "round robin starting from a randomish point". When round robin is used with approximately constant sized chunks, the smallest area runs out of space first, and this is a fatal error.

Workaround: only list local fs dirs in mapred.local.dir with similarly-sized available areas.

I wrote a patch to JobConf (currenly being tested) which uses df to check available space (once a minute or less often) and then uses an efficient roulette selection to do allocation weighted by magnitude of available space.

Comments

[Ari Rabkin]

This is a less pressing issue these days, since you can pass a size to the local dir allocator and it'll do the right thing.
Do people think this is still worth fixing? It should be straightforward to do something roulette-y in LocalDirAllocator.getLocalPathForWrite for unknown-size writes.

[Ari Rabkin]

Patch fixing this issue.

[Ari Rabkin]

downgrading priority

[Hadoop QA]

+1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12386584/hadoop9.patch
against trunk revision 678593.

+1 @author. The patch does not contain any @author tags.

+1 tests included. The patch appears to include 3 new or modified tests.

+1 javadoc. The javadoc tool did not generate any warning messages.

+1 javac. The applied patch does not increase the total number of javac compiler warnings.

+1 findbugs. The patch does not introduce any new Findbugs warnings.

+1 release audit. The applied patch does not increase the total number of release audit warnings.

+1 core tests. The patch passed core unit tests.

+1 contrib tests. The patch passed contrib unit tests.

Test results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2920/testReport/
Findbugs warnings: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2920/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2920/artifact/trunk/build/test/checkstyle-errors.html
Console output: http://hudson.zones.apache.org/hudson/job/Hadoop-Patch/2920/console

This message is automatically generated.

[Owen O'Malley]

I just committed this. Thanks, Ari!

[Hudson]

Integrated in Hadoop-trunk #581 (See http://hudson.zones.apache.org/hudson/job/Hadoop-trunk/581/)