[jira] [Commented] (MAPREDUCE-6357) MultipleOutputs.write() API should document that output committing is not utilized when input path is absolute

["Hadoop QA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6357?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14661962#comment-14661962 ] 

Hadoop QA commented on MAPREDUCE-6357:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | pre-patch |  16m 36s | Pre-patch trunk compilation is healthy. |
| {color:green}+1{color} | @author |   0m  0s | The patch does not contain any @author tags. |
| {color:red}-1{color} | tests included |   0m  0s | The patch doesn't appear to include any new or modified tests.  Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch. |
| {color:green}+1{color} | javac |   7m 52s | There were no new javac warning messages. |
| {color:green}+1{color} | javadoc |   9m 53s | There were no new javadoc warning messages. |
| {color:green}+1{color} | release audit |   0m 24s | The applied patch does not increase the total number of release audit warnings. |
| {color:red}-1{color} | checkstyle |   0m 46s | The applied patch generated  3 new checkstyle issues (total was 29, now 32). |
| {color:green}+1{color} | whitespace |   0m  0s | The patch has no lines that end in whitespace. |
| {color:green}+1{color} | install |   1m 23s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse |   0m 33s | The patch built with eclipse:eclipse. |
| {color:green}+1{color} | findbugs |   1m 26s | The patch does not introduce any new Findbugs (version 3.0.0) warnings. |
| {color:green}+1{color} | mapreduce tests |   1m 47s | Tests passed in hadoop-mapreduce-client-core. |
| | |  40m 43s | |
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|| Subsystem || Report/Notes ||
| Patch URL | http://issues.apache.org/jira/secure/attachment/12749275/MAPREDUCE-6357-1.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / b6265d3 |
| checkstyle |  https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5931/artifact/patchprocess/diffcheckstylehadoop-mapreduce-client-core.txt |
| hadoop-mapreduce-client-core test log | https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5931/artifact/patchprocess/testrun_hadoop-mapreduce-client-core.txt |
| Test Results | https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5931/testReport/ |
| Java | 1.7.0_55 |
| uname | Linux asf903.gq1.ygridcore.net 3.13.0-36-lowlatency #63-Ubuntu SMP PREEMPT Wed Sep 3 21:56:12 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux |
| Console output | https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/5931/console |


This message was automatically generated.

> MultipleOutputs.write() API should document that output committing is not utilized when input path is absolute
> --------------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-6357
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6357
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: documentation
>    Affects Versions: 2.6.0
>            Reporter: Ivan Mitic
>            Assignee: Dustin Cote
>         Attachments: MAPREDUCE-6357-1.patch
>
>
> After spending the afternoon debugging a user job where reduce tasks were failing on retry with the below exception, I think it would be worthwhile to add a note in the MultipleOutputs.write() documentation, saying that absolute paths may cause improper execution of tasks on retry or when MR speculative execution is enabled. 
> {code}
> 2015-04-28 23:13:10,452 WARN [main] org.apache.hadoop.mapred.YarnChild: Exception running child : java.io.IOException: File already exists:wasb://full20150320@bgtstoragefull.blob.core.windows.net/user/hadoop/some/path/block-r-00299.bz2
>        at org.apache.hadoop.fs.azure.NativeAzureFileSystem.create(NativeAzureFileSystem.java:1354)
>        at org.apache.hadoop.fs.azure.NativeAzureFileSystem.create(NativeAzureFileSystem.java:1195)
>        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:908)
>        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:889)
>        at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:786)
>        at org.apache.hadoop.mapreduce.lib.output.TextOutputFormat.getRecordWriter(TextOutputFormat.java:135)
>        at org.apache.hadoop.mapreduce.lib.output.MultipleOutputs.getRecordWriter(MultipleOutputs.java:475)
>        at org.apache.hadoop.mapreduce.lib.output.MultipleOutputs.write(MultipleOutputs.java:433)
>        at com.ancestry.bigtree.hadoop.LevelReducer.processValue(LevelReducer.java:91)
>        at com.ancestry.bigtree.hadoop.LevelReducer.reduce(LevelReducer.java:69)
>        at com.ancestry.bigtree.hadoop.LevelReducer.reduce(LevelReducer.java:14)
>        at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:171)
>        at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:627)
>        at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:389)
>        at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)
>        at java.security.AccessController.doPrivileged(Native Method)
>        at javax.security.auth.Subject.doAs(Subject.java:415)
>        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
>        at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
> {code}
> As discussed in MAPREDUCE-3772, when the baseOutputPath passed to MultipleOutputs.write() is an absolute path (or more precisely a path that resolves outside of the job output-dir), the concept of output committing is not utilized. 
> In this case, the user read thru the MultipleOutputs docs and was assuming that everything will be working fine, as there are blog posts saying that MultipleOutputs does handle output commit. 



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