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
> > >> > >> > > >
> > >> > >> > >
> > >> > >> >
> > >> > >>
> > >> > >
> > >> > >
> > >> >
> > >>
> > >
> > >
> >
>
