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From "Ray Chiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-6441) Improve temporary directory name generation in LocalDistributedCacheManager for concurrent processes
Date Thu, 07 Sep 2017 17:56:00 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-6441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16157338#comment-16157338
] 

Ray Chiang commented on MAPREDUCE-6441:
---------------------------------------

Yeah, but this method has an issue with Pig/Sqoop which actually launches separate MR processes
locally that causes this collision.  I haven't figured out a good way to duplicate simultaneous
directory creation (even multithreaded) reliably, but I'm open to suggestions.

> Improve temporary directory name generation in LocalDistributedCacheManager for concurrent
processes
> ----------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-6441
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-6441
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: William Watson
>            Assignee: Ray Chiang
>         Attachments: HADOOP-10924.02.patch, HADOOP-10924.03.jobid-plus-uuid.patch, MAPREDUCE-6441.004.patch,
MAPREDUCE-6441.005.patch, MAPREDUCE-6441.006.patch
>
>
> Kicking off many sqoop processes in different threads results in:
> {code}
> 2014-08-01 13:47:24 -0400:  INFO - 14/08/01 13:47:22 ERROR tool.ImportTool: Encountered
IOException running import job: java.io.IOException: java.util.concurrent.ExecutionException:
java.io.IOException: Rename cannot overwrite non empty destination directory /tmp/hadoop-hadoop/mapred/local/1406915233073
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapred.LocalDistributedCacheManager.setup(LocalDistributedCacheManager.java:149)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapred.LocalJobRunner$Job.<init>(LocalJobRunner.java:163)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapred.LocalJobRunner.submitJob(LocalJobRunner.java:731)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:432)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1285)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1282)
> 2014-08-01 13:47:24 -0400:  INFO - 	at java.security.AccessController.doPrivileged(Native
Method)
> 2014-08-01 13:47:24 -0400:  INFO - 	at javax.security.auth.Subject.doAs(Subject.java:415)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1548)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapreduce.Job.submit(Job.java:1282)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1303)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.mapreduce.ImportJobBase.doSubmitJob(ImportJobBase.java:186)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.mapreduce.ImportJobBase.runJob(ImportJobBase.java:159)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.mapreduce.ImportJobBase.runImport(ImportJobBase.java:239)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.manager.SqlManager.importQuery(SqlManager.java:645)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:415)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:502)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.Sqoop.run(Sqoop.java:145)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:181)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.Sqoop.runTool(Sqoop.java:220)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.Sqoop.runTool(Sqoop.java:229)
> 2014-08-01 13:47:24 -0400:  INFO - 	at org.apache.sqoop.Sqoop.main(Sqoop.java:238)
> {code}
> If two are kicked off in the same second. The issue is the following lines of code in
the org.apache.hadoop.mapred.LocalDistributedCacheManager class: 
> {code}
>     // Generating unique numbers for FSDownload.
>     AtomicLong uniqueNumberGenerator =
>        new AtomicLong(System.currentTimeMillis());
> {code}
> and 
> {code}
> Long.toString(uniqueNumberGenerator.incrementAndGet())),
> {code}



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