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From Kannan Muthukkaruppan <Kan...@facebook.com>
Subject RE: scanner lease expired/region server shutdown
Date Tue, 26 Jan 2010 15:10:47 GMT

Looking further up in the logs (about 20 minutes prior in the logs when errors first started
happening), I noticed the following. 

btw, ulimit -a shows that I have "open files" set to 64k. Is that not sufficient?

2010-01-25 11:10:21,774 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(10.129.68.212:50010,
storageID=DS-1418567969-10.129.68.212-50010-1263610251776, infoPort=50075, ipcPort=50020):Data\
XceiveServer: java.io.IOException: Too many open files
        at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
        at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:145)
        at sun.nio.ch.ServerSocketAdaptor.accept(ServerSocketAdaptor.java:84)
        at org.apache.hadoop.hdfs.server.datanode.DataXceiverServer.run(DataXceiverServer.java:130)
        at java.lang.Thread.run(Thread.java:619)

2010-01-25 11:10:21,566 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(10.129.68.212:50010,
storageID=DS-1418567969-10.129.68.212-50010-1263610251776, infoPort=50075, ipcPort=50020):Got
\
exception while serving blk_3332344970774019423_10249 to /10.129.68.212:
java.io.FileNotFoundException: /mnt/d1/HDFS-kannan1/current/subdir23/blk_3332344970774019423_10249.meta
(Too many open files)
        at java.io.FileInputStream.open(Native Method)
        at java.io.FileInputStream.<init>(FileInputStream.java:106)
        at org.apache.hadoop.hdfs.server.datanode.FSDataset.getMetaDataInputStream(FSDataset.java:682)
        at org.apache.hadoop.hdfs.server.datanode.BlockSender.<init>(BlockSender.java:97)
        at org.apache.hadoop.hdfs.server.datanode.DataXceiver.readBlock(DataXceiver.java:172)
        at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:95)
        at java.lang.Thread.run(Thread.java:619)



________________________________________
From: Kannan Muthukkaruppan [Kannan@facebook.com]
Sent: Tuesday, January 26, 2010 7:01 AM
To: hbase-dev@hadoop.apache.org
Subject: RE: scanner lease expired/region server shutdown

1. Yes, it is a 5 node, setup.

1 Name Node/4 Data Nodes. Of the 4 DN, one is running the HBase Master, and the other three
are running region servers. ZK is on all the same 5 nodes. Should ideally have separated this
out. The nodes are 16GB, 4 disk machines.

2. I examined the HDFS datanode log on the same machine around that time the problems happened,
and saw this:

2010-01-25 11:33:09,531 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(10.129.68.212:50010,
storageID=DS-1418567969-10.129.68.212-50010-1263610251776, infoPort=50075, ipcPort=\
50020):Got exception while serving blk_5691809099673541164_10475 to /10.129.68.212:
java.net.SocketTimeoutException: 480000 millis timeout while waiting for channel to be ready
for write. ch : java.nio.channels.SocketChannel[connected local=/10.129.68.212:50010 remote=/10.129.68.212:477\
29]
        at org.apache.hadoop.net.SocketIOWithTimeout.waitForIO(SocketIOWithTimeout.java:246)
        at org.apache.hadoop.net.SocketOutputStream.waitForWritable(SocketOutputStream.java:159)
        at org.apache.hadoop.net.SocketOutputStream.transferToFully(SocketOutputStream.java:198)
        at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendChunks(BlockSender.java:313)
        at org.apache.hadoop.hdfs.server.datanode.BlockSender.sendBlock(BlockSender.java:400)
        at org.apache.hadoop.hdfs.server.datanode.DataXceiver.readBlock(DataXceiver.java:180)
        at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:95)
        at java.lang.Thread.run(Thread.java:619)

[For future runs, will try to turn on Java GC logging as well as per your suggestion.]

3.  You wrote <<< There is no line after the above?  A region with a startkey of
0031841132?  >>>

I just cut-paste a section of the PE log and the scan of the '.META.' from shell. But there
were many such regions for which the PE client reported errors of the form:

10/01/25 12:31:37 DEBUG client.HConnectionManager$TableServers: locateRegionInMeta attempt
1 of 10 failed; retrying after sleep of 1000 because: Connection refused
10/01/25 12:31:37 DEBUG client.HConnectionManager$TableServers: Removed .META.,,1 for tableName=.META.
from cache because of TestTable,0015411453,99999999999999
10/01/25 12:31:37 DEBUG client.HConnectionManager$TableServers: Cached location for .META.,,1
is 10.129.68.212:60020

and scan of '.META.' revealed that those regions, such as the 'TestTable,0015411453,99999999999999',
had splitA & splitB portions in META.

<<< Then its a dropped edit of .META.  The parent region -- the one being split got
updates which added the splitA and splitB and its offlining but the new region didn't get
inserted?  The crash happened just at that time?>>>

Didn't fully understand the above.

<<< It would be interesting to take a look at the regionserver logs from that time.
 Please post if you have a moment so we can take a looksee.>>>

Will do. Should I just send it as an attachment to the list? Or is their a recommended way
of doing this?

regards,
Kannan
________________________________________
From: saint.ack@gmail.com [saint.ack@gmail.com] On Behalf Of Stack [stack@duboce.net]
Sent: Monday, January 25, 2010 8:59 PM
To: hbase-dev@hadoop.apache.org
Subject: Re: scanner lease expired/region server shutdown

What J-D said but with ornamentation.  See below.

On Mon, Jan 25, 2010 at 7:14 PM, Kannan Muthukkaruppan
<Kannan@facebook.com> wrote:
> I was doing some brute force testing - running one instance of PerformanceEvaluation
(PE) for writes, and another instance for randomReads.
>

Whats the cluster your hitting like?  That 5-node thingy?  Whats the
hardware profile.


> One of the region servers went down after a while. [This is on 0.20.2]. The region server
log had things like:
>
> 2010-01-25 11:33:39,416 WARN org.apache.hadoop.hbase.regionserver.HLog: IPC Server handler
34 on 60020 took 65190ms appending an edit to hlog; editcount=27878

This is saying that it took 65 seconds to append to hdfs.  What was
going on at that time?  A fat GC in the regionserver or over in a
Datanode?  You can enable GC logging uncommenting stuff in the
hbase-env.sh.   Feed the GC log to https://gchisto.dev.java.net/
(suggested by the zookeeper lads).  Its good for finding the long
pauses.  We should find the logs around the long GC pause.  Its
probably a failed promotion that brought on the stop-the-world GC.  Or
your HDFS was struggling?

I was going to say that the PE puts the worse kind of loading on the
hbase cache -- nothing sticks around -- but looking at your numbers
below, cache seems to be working pretty well.

> 2010-01-25 11:33:39,416 DEBUG org.apache.hadoop.hbase.io.hfile.LruBlockCache: Cache Stats:
Sizes: Total=1815.4441MB (1903631104), Free=581.23096MB (609464832),\
>  Max=2396.675MB (2513095936), Counts: Blocks=28216, Access=10904689, Hit=9313612, Miss=1591077,
Evictions=110, Evicted=414336, Ratios: Hit Ratio=85.40924191474\
> 915%, Miss Ratio=14.590759575366974%, Evicted/Run=3766.69091796875
> 2010-01-25 11:33:39,417 WARN org.apache.hadoop.hbase.regionserver.HLog: IPC Server handler
52 on 60020 took 65195ms appending an edit to hlog; editcount=27879
> 2010-01-25 11:33:39,417 WARN org.apache.hadoop.hbase.regionserver.HLog: IPC Server handler
75 on 60020 took 65195ms appending an edit to hlog; editcount=27880
> 2010-01-25 11:33:39,417 INFO org.apache.hadoop.hbase.regionserver.HRegionServer: Scanner
-5220035164735014996 lease expired
>
> This was followed by:
> 2010-01-25 11:33:39,636 WARN org.apache.zookeeper.ClientCnxn: Exception closing session
0x12652c620520001 to sun.nio.ch.SelectionKeyImpl@788ab708<mailto:sun.nio.ch.SelectionKeyImpl@788ab708>
> java.io.IOException: TIMED OUT

This is the zk timeout.

>
> And also errors like:
> 2010-01-25 11:33:39,692 ERROR org.apache.hadoop.hbase.regionserver.HRegionServer:
> org.apache.hadoop.hbase.UnknownScannerException: Name: -5220035164735014996
>

These will happen after the above.  The regionserver is on its way
down.  Probably emptied the list of outstanding regions.


> Subsequently, I restarted the region server and just started the PE in sequentialWrite
mode. It seems to be off to a really slow start. For several regions, it is printing the following:
>
> 10/01/25 18:12:44 DEBUG client.HConnectionManager$TableServers: locateRegionInMeta attempt
0 of 10 failed; retrying after sleep of 1000 because: region offline: TestTable,0031841132,1264121653303
> 10/01/25 18:12:44 DEBUG client.HConnectionManager$TableServers: Removed .META.,,1 for
tableName=.META. from cache because of TestTable,0032000000,99999999999999
> 10/01/25 18:12:44 DEBUG client.HConnectionManager$TableServers: Cached location for .META.,,1
is 10.129.68.212:60020
> 10/01/25 18:12:45 DEBUG client.HConnectionManager$TableServers: locateRegionInMeta attempt
1 of 10 failed; retrying after sleep of 1000 because: region offline: TestTable,0031841132,1264121653303
> 10/01/25 18:12:45 DEBUG client.HConnectionManager$TableServers: Removed .META.,,1 for
tableName=.META. from cache because of TestTable,0032000000,99999999999999
> [..and so on..]
> 10/01/25 18:12:59 DEBUG client.HConnectionManager$TableServers: Cached location for .META.,,1
is 10.129.68.212:60020
> 10/01/25 18:13:07 DEBUG client.HConnectionManager$TableServers: locateRegionInMeta attempt
8 of 10 failed; retrying after sleep of 16000 because: region offline: TestTable,0031841132,1264121653303
> 10/01/25 18:13:07 DEBUG client.HConnectionManager$TableServers: Removed .META.,,1 for
tableName=.META. from cache because of TestTable,0032000000,99999999999999
>
> When I scan the '.META.', I noticed that most of the regions for which I get the above
error were in the middle of (?) a split. For example:
>
> TestTable,0031841132,126412 column=info:regioninfo, timestamp=1264470099796, value=REGION
=> {NAME => 'TestTa
>  1653303                     ble,0031841132,1264121653303', STARTKEY => '0031841132',
ENDKEY => '0032057774',
>                             ENCODED => 644500792, OFFLINE => true, SPLIT =>
true, TABLE => {{NAME => 'TestTab
>                             le', FAMILIES => [{NAME => 'info', VERSIONS => '3',
COMPRESSION => 'NONE', TTL =>
>                              '2147483647', BLOCKSIZE => '65536', IN_MEMORY => 'false',
BLOCKCACHE => 'true'}]
>                             }}
>  TestTable,0031841132,126412 column=info:server, timestamp=1264121655148, value=10.129.68.214:60020
>  1653303
>  TestTable,0031841132,126412 column=info:serverstartcode, timestamp=1264121655148, value=1264109117245
>  1653303
>  TestTable,0031841132,126412 column=info:splitA, timestamp=1264470099796, value=\000\n0031978284\000\000\000\0
>  1653303                     01&g\016\357\277\275\024\"TestTable,0031841132,1264449401108\000\n0031841132\000\
>                             000\000\005\tTestTable\000\000\000\000\000\002\000\000\000\aIS_ROOT\000\000\000\0
>                             05false\000\000\000\aIS_META\000\000\000\005false\000\000\000\001\a\004info\000\0
>                             00\000\a\000\000\000\vBLOOMFILTER\000\000\000\005false\000\000\000\vCOMPRESSION\0
>                             00\000\000\004NONE\000\000\000\bVERSIONS\000\000\000\0013\000\000\000\003TTL\000\
>                             000\000\n2147483647\000\000\000\tBLOCKSIZE\000\000\000\00565536\000\000\000\tIN_M
>                             EMORY\000\000\000\005false\000\000\000\nBLOCKCACHE\000\000\000\004true\357\277\27
>                             5\337\274#
>  TestTable,0031841132,126412 column=info:splitB, timestamp=1264470099796, value=\000\n0032057774\000\000\000\0
>  1653303                     01&g\016\357\277\275\024\"TestTable,0031978284,1264449401108\000\n0031978284\000\
>                             000\000\005\tTestTable\000\000\000\000\000\002\000\000\000\aIS_ROOT\000\000\000\0
>                             05false\000\000\000\aIS_META\000\000\000\005false\000\000\000\001\a\004info\000\0
>                             00\000\a\000\000\000\vBLOOMFILTER\000\000\000\005false\000\000\000\vCOMPRESSION\0
>                             00\000\000\004NONE\000\000\000\bVERSIONS\000\000\000\0013\000\000\000\003TTL\000\
>                             000\000\n2147483647\000\000\000\tBLOCKSIZE\000\000\000\00565536\000\000\000\tIN_M
>                             EMORY\000\000\000\005false\000\000\000\nBLOCKCACHE\000\000\000\004truej\357\277\2
>                             75\312\262
>
> Any thoughts/ideas on what might be going on? Appreciate any input in helping understand
what might be going on.
>

There is no line after the above?  A region with a startkey of
0031841132?  Then its a dropped edit of .META.  The parent region --
the one being split got updates which added the splitA and splitB and
its offlining but the new region didn't get inserted?  The crash
happened just at that time?

It would be interesting to take a look at the regionserver logs from
that time.  Please post if you have a moment so we can take a looksee.

Above kinda thing is what the master rewrite is about moving state
transitions up to zk so atomic over cluster moving regions through
transitions rather than as here, a multi-row update might not all go
through as things currently work.

St.Ack

> Regards,
> Kannan
>
>
>

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