Filed: https://issues.apache.org/jira/browse/HDFS-2741
> Markus, > > Yeah, unfortunately 1.x/0.20.x it does not have a default XML > entry/documentation on this. But it is definitely present, via the same > string as I'd posted before (note the typo in it, it is intended). > > Please log a JIRA for it to be added to the hdfs-default.xml file as well > (patch against branch-1 is welcome too). For higher versions, this has > already been documented (and renamed to a better name). > > On 02-Jan-2012, at 2:59 PM, Markus Jelsma wrote: > > 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.jel...@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(DataXceiv > >>> er .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.jel...@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$DFSInputStream.chooseDataNode(DFSCli > >>>>> e nt. java:2093) at > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.blockSeekTo(DFSClient > >>>>> . jav a:1897) at > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.read(DFSClient.java:2 > >>>>> 0 48) at java.io.DataInputStream.readFully(DataInputStream.java:178) > >>>>> at > >>>>> org.apache.hadoop.io.DataOutputBuffer$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.nextKe > >>>>> y 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:6 > >>>>> 7 ) 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(UserGroupInforma > >>>>> t 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.nextBlockOutputStrea > >>>>> m (DF SClient.java:3213) at > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2300(DFSClien > >>>>> t .ja va:2406) at > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFS > >>>>> C lie nt.java:2646) > >>>>> > >>>>> 2011-12-29 18:07:58,912 WARN org.apache.hadoop.hdfs.DFSClient: Error > >>>>> Recovery for block blk_-1826030182013954555_13532 bad datanode[0] > >>>>> nodes == null 2011-12-29 18:07:58,912 WARN > >>>>> org.apache.hadoop.hdfs.DFSClient: Could not get block locations. > >>>>> Source file "/user/systems/generate- > >>>>> temp-1325180944829/_temporary/_attempt_201112290956_0012_r_000004_0/f > >>>>> etch list-13/part-00004" - Aborting... > >>>>> 2011-12-29 18:07:59,049 INFO > >>>>> org.apache.hadoop.mapred.TaskLogsTruncater: Initializing logs' > >>>>> truncater with mapRetainSize=-1 and > >>>>> reduceRetainSize=-1 2011-12-29 18:07:59,062 WARN > >>>>> org.apache.hadoop.mapred.Child: Error running child > >>>>> java.io.EOFException > >>>>> > >>>>> at java.io.DataInputStream.readShort(DataInputStream.java:298) > >>>>> at > >>>>> > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.createBlockOutputStr > >>>>> e am( DFSClient.java:3272) at > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.nextBlockOutputStrea > >>>>> m (DF SClient.java:3196) at > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2300(DFSClien > >>>>> t .ja va:2406) at > >>>>> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFS > >>>>> C 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,
