You are viewing a plain text version of this content. The canonical link for it is here.
Posted to common-dev@hadoop.apache.org by "Christian Kunz (JIRA)" <ji...@apache.org> on 2007/07/21 00:56:06 UTC
[jira] Commented: (HADOOP-1612) listing of an output directory
shortly after job completion fails
[ https://issues.apache.org/jira/browse/HADOOP-1612?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12514363 ]
Christian Kunz commented on HADOOP-1612:
----------------------------------------
In many of our applications we use the PIPES interface and create multiple files using libhdfs in the output directory of the task. We rely on the framework to promote the output directory of the winning task among speculatively executed tasks, and to kill and clean the losing tasks completely.
Failure to list files in the output directory is just one of several symptoms of this issue. We occasionally lose files after moving them from the output directory to some other destination, or we still find files in temporary task subdirectories of the output directory. E.g we see log entries like the following (happened 17 seconds after job completion, this task was a killed speculative task).
NOTICE(06:58:08,3086960320): Rename <outputDir>/_task_0120_r_000004_1/4/<filename> to <destinationFile>
I also see log entries on the NameNode several seconds after job completion looking like
2007-07-19 23:57:53,791 INFO org.apache.hadoop.dfs.StateChange: BLOCK* NameSystem.allocateBlock: <outputDir>/_task_0120_r_000068_1/68/<filename> blk_5152182437135923221 is created and added to pendingCreates and pendingCreateBlocks
>From this it looks as if the framework is still active with the output directory even after job completion.
> listing of an output directory shortly after job completion fails
> -----------------------------------------------------------------
>
> Key: HADOOP-1612
> URL: https://issues.apache.org/jira/browse/HADOOP-1612
> Project: Hadoop
> Issue Type: Bug
> Components: mapred
> Affects Versions: 0.14.0
> Reporter: Christian Kunz
> Assignee: Arun C Murthy
> Priority: Blocker
> Fix For: 0.14.0
>
>
> Sometimes, after a job finishes, and another application wants to rename dfs files created by that job, listing of the output directory containing the newly created files fails. File creation and directory listing is done via libhdfs, but it is unlikely that this makes any difference, therefore, I add this to the mapred component.
> It might be a race condition: does the job complete before the files in the output directory are promoted?
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.