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From Markus Jelsma <markus.jel...@openindex.io>
Subject Re: I/O errors reading task output on 20.205.0
Date Mon, 02 Jan 2012 09:29:47 GMT
Harsh,

Are you really sure it's there? When i check the job configuration through the 
web gui it don't see it, it's not assigned a default value it seems.

Thanks

On Friday 30 December 2011 14:12:49 Harsh J wrote:
> Yes your .205 release should have it. It should fix your issue!
> 
> On Fri, Dec 30, 2011 at 6:24 PM, Markus Jelsma
> 
> <markus.jelsma@openindex.io> wrote:
> > Hi, (didn't reply to list before)
> > 
> >> Does your DN log show up any form of errors when you run into this?
> > 
> > Actually, i looked checked again to be sure and noticed errors that i
> > didn't notice before:
> > 
> > 2011-12-29 19:51:01,799 ERROR
> > org.apache.hadoop.hdfs.server.datanode.DataNode:
> > DatanodeRegistration(141.105.120.152:50010,
> > storageID=DS-454617998-141.105.120.152-50010-1324646606851,
> > infoPort=50075, ipcPort=50020):DataXceiver
> > java.io.IOException: xceiverCount 258 exceeds the limit of concurrent
> > xcievers 256
> >        at
> > org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:9
> > 2) at java.lang.Thread.run(Thread.java:662)
> > 
> > but also this one:
> > 
> > 2011-12-29 19:51:00,675 ERROR
> > org.apache.hadoop.hdfs.server.datanode.DataNode:
> > DatanodeRegistration(141.105.120.152:50010,
> > storageID=DS-454617998-141.105.120.152-50010-1324646606851,
> > infoPort=50075, ipcPort=50020):DataXceiver
> > java.io.EOFException
> >        at java.io.DataInputStream.readShort(DataInputStream.java:298)
> >        at
> > org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver
> > .java:351) at
> > org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:1
> > 07) at java.lang.Thread.run(Thread.java:662)
> > 
> >> This happens with just two jobs reading how many files? And how many
> >> DNs are these spread across?
> > 
> > One file, 15 parts spread across five machines.
> > 
> >> I'm thinking its probably something to do with your ulimits for the
> >> running DN processes, but I can't say for sure without taking a look
> >> at the logs.
> > 
> > Ulimits for open files is set to 16k for all machines.
> > 
> >> Some other stuff I can think of, a little blindly:
> >> - What's your dfs.datanode.max.xcievers settings?
> > 
> > I don't know. I increased it for a 0.22.0 test cluster but this is
> > 0.20.205.0 and i haven't seen that configuration directive in the manual
> > for this version. At least not in the hdfs-, core or mapred-default
> > files.
> > 
> >> - Can you ensure 'hadoop classpath' on all nodes reflects the same
> >> output, and no accidental jar mixups?
> > 
> > They are identical. All machines were installed and configured
> > automatically and looking at it i don't see any differences.
> > 
> > Is there such a max.xceivers setting in the 0.20.x branch? Judging from
> > the exception it might be that's the problem.
> > 
> > Thanks!
> > 
> >> Does your DN log show up any form of errors when you run into this?
> >> This happens with just two jobs reading how many files? And how many
> >> DNs are these spread across?
> >> 
> >> I'm thinking its probably something to do with your ulimits for the
> >> running DN processes, but I can't say for sure without taking a look
> >> at the logs.
> >> 
> >> Some other stuff I can think of, a little blindly:
> >> - What's your dfs.datanode.max.xcievers settings?
> >> - Can you ensure 'hadoop classpath' on all nodes reflects the same
> >> output, and no accidental jar mixups?
> >> 
> >> On Thu, Dec 29, 2011 at 11:48 PM, Markus Jelsma
> >> 
> >> <markus.jelsma@openindex.io> wrote:
> >> > We just reproduced it (somehow) by running jobs concurrently reading
> >> > the same data. Two out of three similar jobs died early in the map
> >> > phase with Could not obtain block errors, one finished completely.
> >> > 
> >> > java.io.IOException: Could not obtain block:
> >> > blk_119146860335302651_13067
> >> > file=/user/systems/crawl/crawldb/current/part-00000/data
> >> >        at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSInputStream.chooseDataNode(DFSClie
> >> > nt. java:2093) at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSInputStream.blockSeekTo(DFSClient.
> >> > jav a:1897) at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSInputStream.read(DFSClient.java:20
> >> > 48) at java.io.DataInputStream.readFully(DataInputStream.java:178) at
> >> > org.apache.hadoop.io.DataOutputBuffer$Buffer.write(DataOutputBuffer.ja
> >> > va: 63) at
> >> > org.apache.hadoop.io.DataOutputBuffer.write(DataOutputBuffer.java:101)
> >> > at
> >> > org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:1937)
> >> > at
> >> > org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:2069)
> >> > at
> >> > org.apache.hadoop.mapreduce.lib.input.SequenceFileRecordReader.nextKey
> >> > Val ue(SequenceFileRecordReader.java:68) at
> >> > org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(
> >> > Map Task.java:532) at
> >> > org.apache.hadoop.mapreduce.MapContext.nextKeyValue(MapContext.java:67
> >> > ) at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:143) at
> >> > org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764) at
> >> > org.apache.hadoop.mapred.MapTask.run(MapTask.java:370) at
> >> > org.apache.hadoop.mapred.Child$4.run(Child.java:255)
> >> >        at java.security.AccessController.doPrivileged(Native Method)
> >> >        at javax.security.auth.Subject.doAs(Subject.java:396)
> >> >        at
> >> > org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformat
> >> > ion .java:1059) at org.apache.hadoop.mapred.Child.main(Child.java:249)
> >> > 
> >> > Another job (different but reading the same data) finished the map
> >> > phase but died partially (half of the reducers) and completely
> >> > frooze.
> >> > 
> >> > 2011-12-29 18:07:58,899 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Exception in createBlockOutputStream java.io.EOFException
> >> > 2011-12-29 18:07:58,899 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Abandoning block blk_4748641522370871094_13532
> >> > 2011-12-29 18:07:58,900 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Excluding datanode 141.105.120.154:50010
> >> > 2011-12-29 18:07:58,902 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Exception in createBlockOutputStream java.io.EOFException
> >> > 2011-12-29 18:07:58,902 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Abandoning block blk_-1454920600140944030_13532
> >> > 2011-12-29 18:07:58,903 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Excluding datanode 141.105.120.152:50010
> >> > 2011-12-29 18:07:58,907 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Exception in createBlockOutputStream java.io.IOException: Bad connect
> >> > ack with firstBadLink as 141.105.120.153:50010
> >> > 2011-12-29 18:07:58,907 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Abandoning block blk_3551418605384221738_13532
> >> > 2011-12-29 18:07:58,908 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Excluding datanode 141.105.120.153:50010
> >> > 2011-12-29 18:07:58,910 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Exception in createBlockOutputStream java.io.EOFException
> >> > 2011-12-29 18:07:58,910 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Abandoning block blk_-1826030182013954555_13532
> >> > 2011-12-29 18:07:58,911 INFO org.apache.hadoop.hdfs.DFSClient:
> >> > Excluding datanode 141.105.120.150:50010
> >> > 2011-12-29 18:07:58,911 WARN org.apache.hadoop.hdfs.DFSClient:
> >> > DataStreamer Exception: java.io.IOException: Unable to create new
> >> > block. at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.nextBlockOutputStream
> >> > (DF SClient.java:3213) at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2300(DFSClient
> >> > .ja va:2406) at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSC
> >> > lie nt.java:2646)
> >> > 
> >> > 2011-12-29 18:07:58,912 WARN org.apache.hadoop.hdfs.DFSClient: Error
> >> > Recovery for block blk_-1826030182013954555_13532 bad datanode[0]
> >> > nodes == null 2011-12-29 18:07:58,912 WARN
> >> > org.apache.hadoop.hdfs.DFSClient: Could not get block locations.
> >> > Source file "/user/systems/generate-
> >> > temp-1325180944829/_temporary/_attempt_201112290956_0012_r_000004_0/f
> >> > etch list-13/part-00004" - Aborting...
> >> > 2011-12-29 18:07:59,049 INFO
> >> > org.apache.hadoop.mapred.TaskLogsTruncater: Initializing logs'
> >> > truncater with mapRetainSize=-1 and
> >> > reduceRetainSize=-1 2011-12-29 18:07:59,062 WARN
> >> > org.apache.hadoop.mapred.Child: Error running child
> >> > java.io.EOFException
> >> >        at java.io.DataInputStream.readShort(DataInputStream.java:298)
> >> >        at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.createBlockOutputStre
> >> > am( DFSClient.java:3272) at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.nextBlockOutputStream
> >> > (DF SClient.java:3196) at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2300(DFSClient
> >> > .ja va:2406) at
> >> > org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSC
> >> > lie nt.java:2646) 2011-12-29 18:07:59,064 INFO
> >> > org.apache.hadoop.mapred.Task: Runnning cleanup for the task
> >> > 
> >> > It smells like the datanodes in 20.205.0 don't deal well with
> >> > concurrent jobs, especially handling the same data.
> >> > 
> >> > Is there any advice for this? Again, this does not happen on 20.203.0.
> >> > Many thanks
> >> > 
> >> >> I should add that the failing tasks that ran concurrently all read
> >> >> the same map files from HDFS.
> >> >> 
> >> >> > Hi,
> >> >> > 
> >> >> > We just ran run large scale Apache Nutch jobs in our evaluation
of
> >> >> > 20.205.0 and they all failed. Some of these jobs ran concurrently
> >> >> > with the fair scheduler enabled. These were simple jobs consuming
> >> >> > little RAM. I double checked and there were certainly no RAM
> >> >> > issues.
> >> >> > 
> >> >> > All jobs failed and most tasks had a less than descriptive message.
> >> >> > A few told they dealt with I/O errors reading task output.
> >> >> > However, the data the read is fine. When we ran the same jobs
> >> >> > manually (and some concurrently) some did fine and others died
for
> >> >> > with I/O errors reading task output again!
> >> >> > 
> >> >> > The heap allocation for the reducers is not high but no OOM's
were
> >> >> > reported. Besides the occasional I/O error, which i think is
> >> >> > strange enough, most tasks did not write anything to the logs
that
> >> >> > i can link to this problem.
> >> >> > 
> >> >> > We do not see this happening on our 20.203.0 cluster although
> >> >> > resources and settings are different. 205 is a new high-end cluster
> >> >> > with similar conservative settings but only more mappers/reducers
> >> >> > per node. Resource settings are almost identical. The 203 cluster
> >> >> > has three times as many machines so also more open file
> >> >> > descriptors and threads.
> >> >> > 
> >> >> > Any thoughts to share?
> >> >> > Thanks,

-- 
Markus Jelsma - CTO - Openindex

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