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https://issues.apache.org/jira/browse/PIG-733?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12696244#action_12696244
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Pradeep Kamath commented on PIG-733:
------------------------------------
Tests are not included in this patch since there are existing tests for order
by.
All core unit tests did pass and finbugs gave the same number of warnings with
and without the patch (output below). The excess warnings produced by the patch
have been addressed in the new version of the patch (PIG-733-v2.patch).
{noformat}
=== CORE UNIT TESTS OUTPUT WITH PATCH====
[prade...@afterside:/tmp/PIG-733/trunk]
test-core:
[mkdir] Created dir: /tmp/PIG-733/trunk/build/test/logs
[junit] Running org.apache.pig.test.TestAdd
[junit] Tests run: 1, Failures: 0, Errors: 0, Time elapsed: 0.056 sec
...
[junit] Running org.apache.pig.test.TestTypeCheckingValidatorNoSchema
[junit] Tests run: 13, Failures: 0, Errors: 0, Time elapsed: 0.629 sec
[junit] Running org.apache.pig.test.TestUnion
[junit] Tests run: 3, Failures: 0, Errors: 0, Time elapsed: 49.94 sec
test-contrib:
BUILD SUCCESSFUL
Total time: 77 minutes 47 seconds
=== FINDBUGS OUTPUT WITH PATCH====
[prade...@afterside:/tmp/PIG-733/trunk]
[prade...@chargesize:/tmp/PIG-733/trunk]ant
-Dfindbugs.home=/homes/pradeepk/findbugs-1.3.8 findbugs
Buildfile: build.xml
...
findbugs:
[mkdir] Created dir: /tmp/PIG-733/trunk/build/test/findbugs
[findbugs] Executing findbugs from ant task
[findbugs] Running FindBugs...
[findbugs] Warnings generated: 665
[findbugs] Calculating exit code...
[findbugs] Setting 'bugs found' flag (1)
[findbugs] Exit code set to: 1
[findbugs] Java Result: 1
[findbugs] Output saved to
/tmp/PIG-733/trunk/build/test/findbugs/pig-findbugs-report.xml
[xslt] Processing
/tmp/PIG-733/trunk/build/test/findbugs/pig-findbugs-report.xml to
/tmp/PIG-733/trunk/build/test/findbugs/pig-findbugs-report.html
[xslt] Loading stylesheet
/homes/pradeepk/findbugs-1.3.8/src/xsl/default.xsl
=== FINDBUGS OUTPUT WITHOUT PATCH====
[prade...@chargesize:/tmp/svncheckout/trunk]ant
-Dfindbugs.home=/homes/pradeepk/findbugs-1.3.8 findbugs
Buildfile: build.xml
check-for-findbugs:
...
findbugs:
[mkdir] Created dir: /tmp/svncheckout/trunk/build/test/findbugs
[findbugs] Executing findbugs from ant task
[findbugs] Running FindBugs...
[findbugs] Warnings generated: 665
[findbugs] Calculating exit code...
[findbugs] Setting 'bugs found' flag (1)
[findbugs] Exit code set to: 1
[findbugs] Java Result: 1
[findbugs] Output saved to
/tmp/svncheckout/trunk/build/test/findbugs/pig-findbugs-report.xml
[xslt] Processing
/tmp/svncheckout/trunk/build/test/findbugs/pig-findbugs-report.xml to
/tmp/svncheckout/trunk/build/test/findbugs/pig-findbugs-report.html
[xslt] Loading stylesheet
/homes/pradeepk/findbugs-1.3.8/src/xsl/default.xsl
{noformat}
> Order by sampling dumps entire sample to hdfs which causes dfs "FileSystem
> closed" error on large input
> -------------------------------------------------------------------------------------------------------
>
> Key: PIG-733
> URL: https://issues.apache.org/jira/browse/PIG-733
> Project: Pig
> Issue Type: Bug
> Affects Versions: 0.2.0
> Reporter: Pradeep Kamath
> Assignee: Pradeep Kamath
> Fix For: 0.3.0
>
> Attachments: PIG-733.patch
>
>
> Order by has a sampling job which samples the input and creates a sorted list
> of sample items. CUrrently the number of items sampled is 100 per map task.
> So if the input is large resulting in many maps (say 50,000) the sample is
> big. This sorted sample is stored on dfs. The WeightedRangePartitioner
> computes quantile boundaries and weighted probabilities for repeating values
> in each map by reading the samples file from DFS. In queries with many maps
> (in the order of 50,000) the dfs read of the sample file fails with
> "FileSystem closed" error. This seems to point to a dfs issue wherein a big
> dfs file being read simultaneously by many dfs clients (in this case all
> maps) causes the clients to be closed. However on the pig side, loading the
> sample from each map in the final map reduce job and computing the quantile
> boundaries and weighted probabilities is inefficient. We should do this
> computation through a FindQuantiles udf in the same map reduce job which
> produces the sorted samples. This way lesser data is written to dfs and in
> the final map reduce job, the weightedRangePartitioner needs to just load the
> computed information.
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