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Date: Fri, 27 Aug 2010 18:27:55 -0400 (EDT)
From: "Joydeep Sen Sarma (JIRA)" <jira@apache.org>
To: mapreduce-dev@hadoop.apache.org
Subject: [jira] Reopened: (MAPREDUCE-115) Map tasks are receiving
 FileNotFound Exceptions for spill files on a regular basis and are getting
 killed
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     [ https://issues.apache.org/jira/browse/MAPREDUCE-115?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Joydeep Sen Sarma reopened MAPREDUCE-115:
-----------------------------------------


re-opening. we are seeing this a lot on hadoop-20 (yahoo distribution):

1. reducers not able to fetch map outputs because map side tasktracker cannot locate map output
2. mappers not able to locate previously spilled data

Scott has added logging that is telling us that:
- for #1. that the map output file was actually present/created at the time the map was first reported to be done
- that we have not removed the mapoutput file (from the TT code path deleting the files) before the reducer fetch request came in

so something very fishy - seems like either the files disappear in the interim - or that the localdirallocator is not being able to find things that are actually present. 

> Map tasks are receiving FileNotFound Exceptions for spill files on a regular basis and are getting killed
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-115
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-115
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>            Reporter: Jothi Padmanabhan
>
> The following is the log -- Map tasks are unable to locate the spill files when they are doing the final merge (mergeParts). 
> java.io.FileNotFoundException: File /xxx/mapred-tt/mapred-local/taskTracker/jobcache/job_200808190959_0001/attempt_200808190959_0001_m_000000_0/output/spill23.out does not exist.
> 	at org.apache.hadoop.fs.RawLocalFileSystem.getFileStatus(RawLocalFileSystem.java:420)
> 	at org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:244)
> 	at org.apache.hadoop.fs.FileSystem.getContentSummary(FileSystem.java:682)
> 	at org.apache.hadoop.fs.ChecksumFileSystem$ChecksumFSInputChecker.getFileLength(ChecksumFileSystem.java:218)
> 	at org.apache.hadoop.fs.ChecksumFileSystem$ChecksumFSInputChecker.seek(ChecksumFileSystem.java:259)
> 	at org.apache.hadoop.fs.FSDataInputStream.seek(FSDataInputStream.java:37)
> 	at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.mergeParts(MapTask.java:1102)
> 	at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.flush(MapTask.java:769)
> 	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:255)
> 	at org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:2208)

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