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https://issues.apache.org/jira/browse/MAPREDUCE-1276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12864270#action_12864270
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Amareshwari Sriramadasu commented on MAPREDUCE-1276:
----------------------------------------------------
I repeated the manual testing described in my earlier comment.
I tried to simulate read timeout for m_00001_0 by explicitly adding a sleep in
TaskTracker.MapOutputServlet.sendMapFile(). The attempt fails with error "Too
many fetch failures" as expected.
But most of the times I see m_00002_0 also failing with following error:
{noformat}
Map output lost, rescheduling: error on sending map
attempt_201005051443_0003_m_000002_0 to reduce 1
org.mortbay.jetty.EofException
at org.mortbay.jetty.HttpGenerator.flush(HttpGenerator.java:787)
at org.mortbay.jetty.AbstractGenerator$Output.flush(AbstractGenerator.java:566)
at org.mortbay.jetty.HttpConnection$Output.flush(HttpConnection.java:946)
at java.io.DataOutputStream.flush(DataOutputStream.java:106)
at
org.apache.hadoop.mapred.TaskTracker$MapOutputServlet.sendMapFile(TaskTracker.java:3646)
at
org.apache.hadoop.mapred.TaskTracker$MapOutputServlet.doGet(TaskTracker.java:3517)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:502)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1124)
at
org.apache.hadoop.http.HttpServer$QuotingInputFilter.doFilter(HttpServer.java:766)
at
..
{noformat}
Jothi/Chris, do you think this is an agreeable failure?
I think we should catch this as not an inputException and do a retry.
> Shuffle connection logic needs correction
> ------------------------------------------
>
> Key: MAPREDUCE-1276
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1276
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: task
> Affects Versions: 0.21.0
> Reporter: Jothi Padmanabhan
> Assignee: Amareshwari Sriramadasu
> Priority: Blocker
> Fix For: 0.21.0
>
> Attachments: patch-1276-1.txt, patch-1276.txt
>
>
> While looking at the code with Amareshwari, we realized that
> {{Fetcher#copyFromHost}} marks connection as successful when
> {{url.openConnection}} returns. This is wrong. Connection is done inside
> implicitly inside {{getInputStream}}; we need to split {{getInputStream}}
> into {{connect}} and {{getInputStream}} to handle the connection and read
> time out strategies correctly.
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