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From Uma Maheswara Rao G 72686 <mahesw...@huawei.com>
Subject Re: Never ending reduce jobs, error Error reading task outputConnection refused
Date Fri, 04 Nov 2011 15:44:57 GMT
----- Original Message -----
From: Russell Brown <misterruss@gmail.com>
Date: Friday, November 4, 2011 9:11 pm
Subject: Re: Never ending reduce jobs, error Error reading task outputConnection refused
To: mapreduce-user@hadoop.apache.org

> 
> On 4 Nov 2011, at 15:35, Uma Maheswara Rao G 72686 wrote:
> 
> > This problem may come if you dont configure the hostmappings 
> properly.> Can you check whether your tasktrackers are pingable 
> from each other with the configured hosts names?
> 
> 
> Hi,
> Thanks for replying so fast!
> 
> Hostnames? I use IP addresses in the slaves config file, and via 
> IP addresses everyone can ping everyone else, do I need to set up 
> hostnames too?
Yes, can you configure hostname mappings and check..
> 
> Cheers
> 
> Russell
> > 
> > Regards,
> > Uma
> > ----- Original Message -----
> > From: Russell Brown <misterruss@gmail.com>
> > Date: Friday, November 4, 2011 9:00 pm
> > Subject: Never ending reduce jobs, error Error reading task 
> outputConnection refused
> > To: mapreduce-user@hadoop.apache.org
> > 
> >> Hi,
> >> I have a cluster of 4 tasktracker/datanodes and 1 
> >> JobTracker/Namenode. I can run small jobs on this cluster fine 
> >> (like up to a few thousand keys) but more than that and I start 
> >> seeing errors like this:
> >> 
> >> 
> >> 11/11/04 08:16:08 INFO mapred.JobClient: Task Id : 
> >> attempt_201111040342_0006_m_000005_0, Status : FAILED
> >> Too many fetch-failures
> >> 11/11/04 08:16:08 WARN mapred.JobClient: Error reading task 
> >> outputConnection refused
> >> 11/11/04 08:16:08 WARN mapred.JobClient: Error reading task 
> >> outputConnection refused
> >> 11/11/04 08:16:13 INFO mapred.JobClient:  map 97% reduce 1%
> >> 11/11/04 08:16:25 INFO mapred.JobClient:  map 100% reduce 1%
> >> 11/11/04 08:17:20 INFO mapred.JobClient: Task Id : 
> >> attempt_201111040342_0006_m_000010_0, Status : FAILED
> >> Too many fetch-failures
> >> 11/11/04 08:17:20 WARN mapred.JobClient: Error reading task 
> >> outputConnection refused
> >> 11/11/04 08:17:20 WARN mapred.JobClient: Error reading task 
> >> outputConnection refused
> >> 11/11/04 08:17:24 INFO mapred.JobClient:  map 97% reduce 1%
> >> 11/11/04 08:17:36 INFO mapred.JobClient:  map 100% reduce 1%
> >> 11/11/04 08:19:20 INFO mapred.JobClient: Task Id : 
> >> attempt_201111040342_0006_m_000011_0, Status : FAILED
> >> Too many fetch-failures
> >> 
> >> 
> >> 
> >> I have no IDEA what this means. All my nodes can ssh to each 
> >> other, pass wordlessly, all the time.
> >> 
> >> On the individual data/task nodes the logs have errors like this:
> >> 
> >> 2011-11-04 08:24:42,514 WARN 
> org.apache.hadoop.mapred.TaskTracker: 
> >> getMapOutput(attempt_201111040342_0006_m_000015_0,2) failed :
> >> org.apache.hadoop.util.DiskChecker$DiskErrorException: Could 
> not 
> >> find 
> taskTracker/vagrant/jobcache/job_201111040342_0006/attempt_201111040342_0006_m_000015_0/output/file.out.index
in any of the configured local directories
> >> 	at 
> >> 
> org.apache.hadoop.fs.LocalDirAllocator$AllocatorPerContext.getLocalPathToRead(LocalDirAllocator.java:429)
at org.apache.hadoop.fs.LocalDirAllocator.getLocalPathToRead(LocalDirAllocator.java:160)
> >> 	at 
> >> 
> org.apache.hadoop.mapred.TaskTracker$MapOutputServlet.doGet(TaskTracker.java:3543)	at
javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
> >> 	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
> >> 	at 
> >> 
> org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1221)
> >> 	at 
> >> 
> org.apache.hadoop.http.HttpServer$QuotingInputFilter.doFilter(HttpServer.java:816)	at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1212)
> >> 	at 
> >> 
> org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:399)	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
> >> 	at 
> >> 
> org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
> >> 	at 
> >> 
> org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)	at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
> >> 	at 
> >> 
> org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)	at org.mortbay.jetty.Server.handle(Server.java:326)
> >> 	at 
> >> 
> org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)	at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:928)
> >> 	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549)
> >> 	at 
> org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)>> 
> 	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
> >> 	at 
> >> 
> org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)	at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
> >> 
> >> 2011-11-04 08:24:42,514 WARN 
> org.apache.hadoop.mapred.TaskTracker: 
> >> Unknown child with bad map output: 
> >> attempt_201111040342_0006_m_000015_0. Ignored.
> >> 
> >> 
> >> Are they related? What d any of the mean?
> >> 
> >> If I use a much smaller amount of data I don't see any of these 
> >> errors and everything works fine, so I guess they are to do 
> with 
> >> some resource (though what I don't know?) Looking at 
> >> MASTERNODE:50070/dfsnodelist.jsp?whatNodes=LIVE
> >> I see that datanodes have ample disk space, that isn't it…
> >> 
> >> Any help at all really appreciated. Searching for the errors on 
> >> Google has me nothing, reading the Hadoop definitive guide as 
> me 
> >> nothing.
> >> Many thanks in advance
> >> 
> >> Russell
> 
> 
Regards,
Uma

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