Hi Ted, Nicholas, Thanks for the comments. We found some issues with lease recovery and I patched HBASE 8354 to ensure we don't see data loss. Could you please look at HDFS 4721 and HBASE 8389 ?
Thanks Varun On Sat, Apr 20, 2013 at 10:52 AM, Varun Sharma <[email protected]> wrote: > The important thing to note is the block for this rogue WAL is > UNDER_RECOVERY state. I have repeatedly asked HDFS dev if the stale node > thing kicks in correctly for UNDER_RECOVERY blocks but failed. > > > On Sat, Apr 20, 2013 at 10:47 AM, Varun Sharma <[email protected]>wrote: > >> Hi Nicholas, >> >> Regarding the following, I think this is not a recovery - the file below >> is an HFIle and is being accessed on a get request. On this cluster, I >> don't have block locality. I see these exceptions for a while and then they >> are gone, which means the stale node thing kicks in. >> >> 2013-04-19 00:27:28,432 WARN org.apache.hadoop.hdfs.DFSClient: Failed to >> connect to /10.156.194.94:50010 for file >> /hbase/feeds/1479495ad2a02dceb41f093ebc29fe4f/home/ >> 02f639bb43944d4ba9abcf58287831c0 >> for block >> >> This is the real bummer. The stale datanode is 1st even 90 seconds >> afterwards. >> >> *2013-04-19 00:28:35*,777 WARN >> org.apache.hadoop.hbase.regionserver.SplitLogWorker: log splitting of >> hdfs:// >> ec2-107-20-237-30.compute-1.amazonaws.com/hbase/.logs/ip-10-156-194-94.ec2.internal,60020,1366323217601-splitting/ip-10-156-194-94.ec2.internal%2C60020%2C1366323217601.1366331156141failed, >> returning error >> java.io.IOException: Cannot obtain block length for >> LocatedBlock{BP-696828882-10.168.7.226-1364886167971:blk_-5723958680970112840_174056; >> getBlockSize()=0; corrupt=false; offset=0; locs=*[10.156.194.94:50010, >> 10.156.192.106:50010, 10.156.195.38:50010]}* >> >---at >> org.apache.hadoop.hdfs.DFSInputStream.readBlockLength(DFSInputStream.java:238) >> >---at >> org.apache.hadoop.hdfs.DFSInputStream.fetchLocatedBlocksAndGetLastBlockLength(DFSInputStream.java:182) >> >---at >> org.apache.hadoop.hdfs.DFSInputStream.openInfo(DFSInputStream.java:124) >> >---at >> org.apache.hadoop.hdfs.DFSInputStream.<init>(DFSInputStream.java:117) >> >---at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:1080) >> >---at >> org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:245) >> >---at >> org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:78) >> >---at >> org.apache.hadoop.io.SequenceFile$Reader.openFile(SequenceFile.java:1787) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader$WALReader.openFile(SequenceFileLogReader.java:62) >> >---at >> org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1707) >> >---at >> org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1728) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader$WALReader.<init>(SequenceFileLogReader.java:55) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader.init(SequenceFileLogReader.java:175) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.HLog.getReader(HLog.java:717) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.getReader(HLogSplitter.java:821) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.getReader(HLogSplitter.java:734) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.splitLogFile(HLogSplitter.java:381) >> >---at >> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.splitLogFile(HLogSplitter.java:348) >> >---at >> org.apache.hadoop.hbase.regionserver.SplitLogWorker$1.exec(SplitLogWorker.java:111) >> >---at >> org.apache.hadoop.hbase.regionserver.SplitLogWorker.grabTask(SplitLogWorker.java:264) >> >---at >> org.apache.hadoop.hbase.regionserver.SplitLogWorker.taskLoop(SplitLogWorker.java:195) >> >---at >> org.apache.hadoop.hbase.regionserver.SplitLogWorker.run(SplitLogWorker.java:163) >> >---at java.lang.Thread.run(Thread.java:662) >> >> >> >> On Sat, Apr 20, 2013 at 1:16 AM, Nicolas Liochon <[email protected]>wrote: >> >>> Hi, >>> >>> I looked at it again with a fresh eye. As Varun was saying, the root >>> cause >>> is the wrong order of the block locations. >>> >>> The root cause of the root cause is actually simple: HBASE started the >>> recovery while the node was not yet stale from an HDFS pov. >>> >>> Varun mentioned this timing: >>> Lost Beat: 27:30 >>> Became stale: 27:50 - * this is a guess and reverse engineered (stale >>> timeout 20 seconds) >>> Became dead: 37:51 >>> >>> But the recovery started at 27:13 (15 seconds before we have this log >>> line) >>> 2013-04-19 00:27:28,432 WARN org.apache.hadoop.hdfs.DFSClient: Failed to >>> connect to /10.156.194.94:50010 for file >>> >>> /hbase/feeds/1479495ad2a02dceb41f093ebc29fe4f/home/02f639bb43944d4ba9abcf58287831c0 >>> for block >>> >>> BP-696828882-10.168.7.226-1364886167971:blk_-5977178030490858298_99853:java.net.SocketTimeoutException: >>> 15000 millis timeout while waiting for channel to be ready for connect. >>> ch >>> : java.nio.channels.SocketChannel[connection-pending remote=/ >>> 10.156.194.94:50010] >>> >>> So when we took the blocks from the NN, the datanode was not stale, so >>> you >>> have the wrong (random) order. >>> >>> ZooKeeper can expire a session before the timeout. I don't what why it >>> does >>> this in this case, but I don't consider it as a ZK bug: if ZK knows that >>> a >>> node is dead, it's its role to expire the session. There is something >>> more >>> fishy: we started the recovery while the datanode was still responding to >>> heartbeat. I don't know why. Maybe the OS has been able to kill 15 the RS >>> before vanishing away. >>> >>> Anyway, we then have an exception when we try to connect, because the RS >>> does not have a TCP connection to this datanode. And this is retried many >>> times. >>> >>> You would not have this with trunk, because HBASE-6435 reorders the >>> blocks >>> inside the client, using an information not available to the NN, >>> excluding >>> the datanode of the region server under recovery. >>> >>> Some conclusions: >>> - we should likely backport hbase-6435 to 0.94. >>> - I will revive HDFS-3706 and HDFS-3705 (the non hacky way to get >>> hbase-6435). >>> - There are some stuff that could be better in HDFS. I will see. >>> - I'm worried by the SocketTimeoutException. We should get NoRouteToHost >>> at a moment, and we don't. That's also why it takes ages. I think it's an >>> AWS thing, but it brings to issue: it's slow, and, in HBase, you don't >>> know >>> if the operation could have been executed or not, so it adds complexity >>> to >>> some scenarios. If someone with enough network and AWS knowledge could >>> clarify this point it would be great. >>> >>> Cheers, >>> >>> Nicolas >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> On Fri, Apr 19, 2013 at 10:10 PM, Varun Sharma <[email protected]> >>> wrote: >>> >>> > This is 0.94.3 hbase... >>> > >>> > >>> > On Fri, Apr 19, 2013 at 1:09 PM, Varun Sharma <[email protected]> >>> wrote: >>> > >>> > > Hi Ted, >>> > > >>> > > I had a long offline discussion with nicholas on this. Looks like the >>> > last >>> > > block which was still being written too, took an enormous time to >>> > recover. >>> > > Here's what happened. >>> > > a) Master split tasks and region servers process them >>> > > b) Region server tries to recover lease for each WAL log - most >>> cases are >>> > > noop since they are already rolled over/finalized >>> > > c) The last file lease recovery takes some time since the crashing >>> server >>> > > was writing to it and had a lease on it - but basically we have the >>> > lease 1 >>> > > minute after the server was lost >>> > > d) Now we start the recovery for this but we end up hitting the stale >>> > data >>> > > node which is puzzling. >>> > > >>> > > It seems that we did not hit the stale datanode when we were trying >>> to >>> > > recover the finalized WAL blocks with trivial lease recovery. >>> However, >>> > for >>> > > the final block, we hit the stale datanode. Any clue why this might >>> be >>> > > happening ? >>> > > >>> > > Varun >>> > > >>> > > >>> > > On Fri, Apr 19, 2013 at 10:40 AM, Ted Yu <[email protected]> >>> wrote: >>> > > >>> > >> Can you show snippet from DN log which mentioned UNDER_RECOVERY ? >>> > >> >>> > >> Here is the criteria for stale node checking to kick in (from >>> > >> >>> > >> >>> > >>> https://issues.apache.org/jira/secure/attachment/12544897/HDFS-3703-trunk-read-only.patch >>> > >> ): >>> > >> >>> > >> + * Check if the datanode is in stale state. Here if >>> > >> + * the namenode has not received heartbeat msg from a >>> > >> + * datanode for more than staleInterval (default value is >>> > >> + * {@link >>> > >> DFSConfigKeys#DFS_NAMENODE_STALE_DATANODE_INTERVAL_MILLI_DEFAULT}), >>> > >> + * the datanode will be treated as stale node. >>> > >> >>> > >> >>> > >> On Fri, Apr 19, 2013 at 10:28 AM, Varun Sharma <[email protected] >>> > >>> > >> wrote: >>> > >> >>> > >> > Is there a place to upload these logs ? >>> > >> > >>> > >> > >>> > >> > On Fri, Apr 19, 2013 at 10:25 AM, Varun Sharma < >>> [email protected]> >>> > >> > wrote: >>> > >> > >>> > >> > > Hi Nicholas, >>> > >> > > >>> > >> > > Attached are the namenode, dn logs (of one of the healthy >>> replicas >>> > of >>> > >> the >>> > >> > > WAL block) and the rs logs which got stuch doing the log split. >>> > Action >>> > >> > > begins at 2013-04-19 00:27*. >>> > >> > > >>> > >> > > Also, the rogue block is 5723958680970112840_174056. Its very >>> > >> interesting >>> > >> > > to trace this guy through the HDFS logs (dn and nn). >>> > >> > > >>> > >> > > Btw, do you know what the UNDER_RECOVERY stage is for, in HDFS ? >>> > Also >>> > >> > does >>> > >> > > the stale node stuff kick in for that state ? >>> > >> > > >>> > >> > > Thanks >>> > >> > > Varun >>> > >> > > >>> > >> > > >>> > >> > > On Fri, Apr 19, 2013 at 4:00 AM, Nicolas Liochon < >>> [email protected] >>> > >> > >wrote: >>> > >> > > >>> > >> > >> Thanks for the detailed scenario and analysis. I'm going to >>> have a >>> > >> look. >>> > >> > >> I can't access the logs ( >>> ec2-107-20-237-30.compute-1.amazonaws.com >>> > >> > >> timeouts), could you please send them directly to me? >>> > >> > >> >>> > >> > >> Thanks, >>> > >> > >> >>> > >> > >> Nicolas >>> > >> > >> >>> > >> > >> >>> > >> > >> On Fri, Apr 19, 2013 at 12:46 PM, Varun Sharma < >>> > [email protected]> >>> > >> > >> wrote: >>> > >> > >> >>> > >> > >> > Hi Nicholas, >>> > >> > >> > >>> > >> > >> > Here is the failure scenario, I have dug up the logs. >>> > >> > >> > >>> > >> > >> > A machine fails and stops accepting/transmitting traffic. The >>> > >> HMaster >>> > >> > >> > starts the distributed split for 13 tasks. There are 12 >>> region >>> > >> > servers. >>> > >> > >> 12 >>> > >> > >> > tasks succeed but the 13th one takes a looong time. >>> > >> > >> > >>> > >> > >> > Zookeeper timeout is set to 30 seconds. Stale node timeout >>> is 20 >>> > >> > >> seconds. >>> > >> > >> > Both patches are there. >>> > >> > >> > >>> > >> > >> > a) Machine fails around 27:30 >>> > >> > >> > b) Master starts the split around 27:40 and submits the >>> tasks. >>> > The >>> > >> one >>> > >> > >> task >>> > >> > >> > which fails seems to be the one which contains the WAL being >>> > >> currently >>> > >> > >> > written to: >>> > >> > >> > >>> > >> > >> > 2013-04-19 00:27:44,325 INFO >>> > >> > >> > org.apache.hadoop.hbase.regionserver.wal.HLogSplitter: >>> Splitting >>> > >> hlog: >>> > >> > >> > hdfs:// >>> > >> > >> > >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> ec2-107-20-237-30.compute-1.amazonaws.com/hbase/.logs/ip-10-156-194-94.ec2.internal,60020,1366323217601-splitting/ip-10-156-194-94.ec2.internal%2C60020%2C1366323217601.1366331156141 >>> > >> > >> > , >>> > >> > >> > length=0 >>> > >> > >> > >>> > >> > >> > Basically this region server picks up the task but finds the >>> > >> length of >>> > >> > >> this >>> > >> > >> > file to be 0 and drops. This happens again >>> > >> > >> > >>> > >> > >> > c) Finally another region server picks up the task but it >>> ends up >>> > >> > going >>> > >> > >> to >>> > >> > >> > the bad datanode which should not happen because of the stale >>> > node >>> > >> > >> timeout) >>> > >> > >> > Unfortunately it hits the 45 retries and a connect timeout >>> of 20 >>> > >> > seconds >>> > >> > >> > every time. This delays recovery significantly. Now I guess >>> > >> reducing # >>> > >> > >> of >>> > >> > >> > retries to 1 is one possibility. >>> > >> > >> > But then the namenode logs are very interesting. >>> > >> > >> > >>> > >> > >> > d) Namenode seems to be in cyclic lease recovery loop until >>> the >>> > >> node >>> > >> > is >>> > >> > >> > marked dead. There is this one last block which exhibits >>> this. >>> > >> > >> > >>> > >> > >> > 2013-04-19 00:28:09,744 INFO BlockStateChange: BLOCK* blk_-* >>> > >> > >> > 5723958680970112840_174056*{blockUCState=UNDER_RECOVERY, >>> > >> > >> > primaryNodeIndex=1, >>> > >> > >> > replicas=[ReplicaUnderConstruction[10.156.194.94:50010|RBW], >>> > >> > >> > ReplicaUnderConstruction[10.156.192.106:50010|RBW], >>> > >> > >> > ReplicaUnderConstruction[10.156.195.38:50010|RBW]]} recovery >>> > >> started, >>> > >> > >> > primary=10.156.192.106:50010 >>> > >> > >> > 2013-04-19 00:28:09,744 WARN >>> org.apache.hadoop.hdfs.StateChange: >>> > >> DIR* >>> > >> > >> > NameSystem.internalReleaseLease: File >>> > >> > >> > >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> /hbase/.logs/ip-10-156-194-94.ec2.internal,60020,1366323217601-splitting/ip-10-156-194-94.ec2.internal%2C60020%2C1366323217601.1366331156141 >>> > >> > >> > has not been closed. Lease recovery is in progress. >>> RecoveryId = >>> > >> > 174413 >>> > >> > >> for >>> > >> > >> > block >>> > blk_-5723958680970112840_174056{blockUCState=UNDER_RECOVERY, >>> > >> > >> > primaryNodeIndex=1, >>> > >> > >> > replicas=[ReplicaUnderConstruction[10.156.194.94:50010|RBW], >>> > >> > >> > ReplicaUnderConstruction[10.156.192.106:50010|RBW], >>> > >> > >> > ReplicaUnderConstruction[10.156.195.38:50010|RBW]]} >>> > >> > >> > >>> > >> > >> > I see this over and over again in the logs until the >>> datanode is >>> > >> > marked >>> > >> > >> > dead. It seems to be cycling through the replicas for this >>> WAL >>> > >> block >>> > >> > and >>> > >> > >> > trying to add it to the recovery list. I looked at the code >>> and >>> > it >>> > >> > says: >>> > >> > >> > >>> > >> > >> > // Cannot close file right now, since the last block >>> > requires >>> > >> > >> > recovery. >>> > >> > >> > // This may potentially cause infinite loop in lease >>> > recovery >>> > >> > >> > // if there are no valid replicas on data-nodes. >>> > >> > >> > NameNode.stateChangeLog.warn( >>> > >> > >> > "DIR* NameSystem.internalReleaseLease: " + >>> > >> > >> > "File " + src + " has not been closed." + >>> > >> > >> > " Lease recovery is in progress. " + >>> > >> > >> > "RecoveryId = " + blockRecoveryId + " for >>> block >>> > " + >>> > >> > >> > lastBlock); >>> > >> > >> > break; >>> > >> > >> > >>> > >> > >> > Eventually for this block, we get >>> > >> > >> > >>> > >> > >> > 2013-04-19 00:41:20,736 INFO >>> > >> > >> > org.apache.hadoop.hdfs.server.namenode.FSNamesystem: >>> > >> > >> > >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> commitBlockSynchronization(lastblock=BP-696828882-10.168.7.226-1364886167971:blk_- >>> > >> > >> > *5723958680970112840_174056*, newgenerationstamp=174413, >>> > >> > >> > newlength=119148648, newtargets=[10.156.192.106:50010, >>> > >> > >> 10.156.195.38:50010 >>> > >> > >> > ], >>> > >> > >> > closeFile=true, deleteBlock=false) >>> > >> > >> > 2013-04-19 00:41:20,736 ERROR >>> > >> > >> > org.apache.hadoop.security.UserGroupInformation: >>> > >> > >> PriviledgedActionException >>> > >> > >> > as:hdfs (auth:SIMPLE) cause:java.io.IOException: Block >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> (=BP-696828882-10.168.7.226-1364886167971:blk_-5723958680970112840_174056) >>> > >> > >> > not found >>> > >> > >> > 2013-04-19 00:41:20,736 INFO org.apache.hadoop.ipc.Server: >>> IPC >>> > >> Server >>> > >> > >> > handler 35 on 8020, call >>> > >> > >> > >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol.commitBlockSynchronization >>> > >> > >> > from 10.156.192.106:53271: error: java.io.IOException: Block >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> (=BP-696828882-10.168.7.226-1364886167971:blk_-5723958680970112840_174056) >>> > >> > >> > not found >>> > >> > >> > >>> > >> > >> > On the datanode side, i see a call for recover blocks - I see >>> > that >>> > >> a >>> > >> > >> write >>> > >> > >> > pipeline is there, which gets terminated with some socket >>> > >> timeouts... >>> > >> > >> > >>> > >> > >> > 00:28:11,471 INFO >>> > org.apache.hadoop.hdfs.server.datanode.DataNode: >>> > >> > >> NameNode >>> > >> > >> > at >>> > ec2-107-20-237-30.compute-1.amazonaws.com/10.168.7.226:8020calls >>> > >> > >> > >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> recoverBlock(BP-696828882-10.168.7.226-1364886167971:blk_-5723958680970112840_174056, >>> > >> > >> > targets=[10.156.194.94:50010, 10.156.192.106:50010, >>> > >> > 10.156.195.38:50010 >>> > >> > >> ], >>> > >> > >> > newGenerationStamp=174413) >>> > >> > >> > >>> > >> > >> > Not sure but this looks like a case where data could be lost >>> ? >>> > >> > >> > >>> > >> > >> > Varun >>> > >> > >> > >>> > >> > >> > >>> > >> > >> > On Fri, Apr 19, 2013 at 12:38 AM, Nicolas Liochon < >>> > >> [email protected]> >>> > >> > >> > wrote: >>> > >> > >> > >>> > >> > >> > > Hey Varun, >>> > >> > >> > > >>> > >> > >> > > Could you please share the logs and the configuration >>> (hdfs / >>> > >> hbase >>> > >> > >> > > settings + cluster description). What's the failure >>> scenario? >>> > >> > >> > > From an HDFS pov, HDFS 3703 does not change the dead node >>> > status. >>> > >> > But >>> > >> > >> > these >>> > >> > >> > > node will be given the lowest priority when reading. >>> > >> > >> > > >>> > >> > >> > > >>> > >> > >> > > Cheers, >>> > >> > >> > > >>> > >> > >> > > Nicolas >>> > >> > >> > > >>> > >> > >> > > >>> > >> > >> > > On Fri, Apr 19, 2013 at 3:01 AM, Varun Sharma < >>> > >> [email protected]> >>> > >> > >> > wrote: >>> > >> > >> > > >>> > >> > >> > > > Hi, >>> > >> > >> > > > >>> > >> > >> > > > We are facing problems with really slow HBase region >>> server >>> > >> > >> recoveries >>> > >> > >> > ~ >>> > >> > >> > > 20 >>> > >> > >> > > > minuted. Version is hbase 0.94.3 compiled with >>> > >> hadoop.profile=2.0. >>> > >> > >> > > > >>> > >> > >> > > > Hadoop version is CDH 4.2 with HDFS 3703 and HDFS 3912 >>> > patched >>> > >> and >>> > >> > >> > stale >>> > >> > >> > > > node timeouts configured correctly. Time for dead node >>> > >> detection >>> > >> > is >>> > >> > >> > still >>> > >> > >> > > > 10 minutes. >>> > >> > >> > > > >>> > >> > >> > > > We see that our region server is trying to read an HLog >>> is >>> > >> stuck >>> > >> > >> there >>> > >> > >> > > for >>> > >> > >> > > > a long time. Logs here: >>> > >> > >> > > > >>> > >> > >> > > > 2013-04-12 21:14:30,248 WARN >>> > org.apache.hadoop.hdfs.DFSClient: >>> > >> > >> Failed >>> > >> > >> > to >>> > >> > >> > > > connect to /10.156.194.251:50010 for file >>> > >> > >> > > > >>> > >> > >> > > > >>> > >> > >> > > >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> /hbase/feeds/fbe25f94ed4fa37fb0781e4a8efae142/home/1d102c5238874a5d82adbcc09bf06599 >>> > >> > >> > > > for block >>> > >> > >> > > > >>> > >> > >> > > > >>> > >> > >> > > >>> > >> > >> > >>> > >> > >> >>> > >> > >>> > >> >>> > >>> BP-696828882-10.168.7.226-1364886167971:blk_-3289968688911401881_9428:java.net.SocketTimeoutException: >>> > >> > >> > > > 15000 millis timeout while waiting for channel to be >>> ready >>> > for >>> > >> > read. >>> > >> > >> > ch : >>> > >> > >> > > > java.nio.channels.SocketChannel[connected local=/ >>> > >> > >> 10.156.192.173:52818 >>> > >> > >> > > > remote=/ >>> > >> > >> > > > 10.156.194.251:50010] >>> > >> > >> > > > >>> > >> > >> > > > I would think that HDFS 3703 would make the server fail >>> fast >>> > >> and >>> > >> > go >>> > >> > >> to >>> > >> > >> > > the >>> > >> > >> > > > third datanode. Currently, the recovery seems way too >>> slow >>> > for >>> > >> > >> > production >>> > >> > >> > > > usage... >>> > >> > >> > > > >>> > >> > >> > > > Varun >>> > >> > >> > > > >>> > >> > >> > > >>> > >> > >> > >>> > >> > >> >>> > >> > > >>> > >> > > >>> > >> > >>> > >> >>> > > >>> > > >>> > >>> >> >> >
