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From Nanheng Wu <nanhen...@gmail.com>
Subject Re: Disabling a table taking very long time
Date Tue, 01 Mar 2011 01:04:51 GMT
I issued two more disable commands and looked at the .META RS. The
last log entry looks like:

11/03/01 00:29:14 INFO regionserver.HLog: Roll
/hbase/.logs/<RS_HOSTNAME>,60020,1298935751670/hlog
.dat.1298935752660, entries=13527, calcsize=3839046, filesize=2560143.
New hlog /hbase/.logs/<RS_HOSTNAME>,60020,1298935751670/hlog.dat.1298939354072

I issued the command at: 00:34:59, the client debug message has
nothing but "11/03/01 00:34:59 DEBUG zookeeper.ClientCnxn: Got ping
response for sessionid:0x12e6e938e9c000b after 90ms" until 00:47:19.
Then all of a sudden it outputs the following:

0:47:28 DEBUG client.HConnectionManager$TableServers: Cache hit for
row <> in tableName .META.: location server 10.146.14.38:60020,
location region name .META.,,1
11/03/01 00:47:28 DEBUG zookeeper.ZooKeeperWrapper: Read ZNode
/hbase/root-region-server got 10.146.14.38:60020
11/03/01 00:47:28 DEBUG client.HConnectionManager$TableServers: Found
ROOT at 10.146.14.38:60020
11/03/01 00:47:28 DEBUG client.HConnectionManager$TableServers: Cached
location for .META.,,1 is 10.146.14.38:60020
11/03/01 00:47:30 DEBUG client.HConnectionManager$TableServers:
Rowscanned=261, rowsOffline=3
11/03/01 00:47:30 DEBUG client.HBaseAdmin: Sleep. Waiting for all
regions to be disabled from myTable
11/03/01 00:47:31 DEBUG client.HBaseAdmin: Wake. Waiting for all
regions to be disabled from myTable

Here's the full thread dump of the .META RS from 00:34:59 to  00:47:31
http://pastebin.com/Ywwx8afQ

I hope I compiled some useful information here. I am pretty lost at
this point, I would really appreciate your help!

Thanks!



On Mon, Feb 28, 2011 at 2:58 PM, Jean-Daniel Cryans <jdcryans@apache.org> wrote:
> Ok so no debug from the disable command? BTW you should output your GC
> somewhere else like the .out file or a completely separate file.
>
> J-D
>
> On Mon, Feb 28, 2011 at 2:54 PM, Nanheng Wu <nanhengwu@gmail.com> wrote:
>> I see, so I should jstack the .META region. I'll do that.
>>
>> The master log pretty much looks like this: should I grep for
>> something specific?
>>
>> 11/02/28 22:52:56 INFO master.BaseScanner: RegionManager.rootScanner
>> scan of 1 row(s) of meta region complete
>> 2011-02-28T22:52:57.138+0000: 263241.014: [GC 263241.014: [ParNew:
>> 19136K->2112K(19136K), 0.0033350 secs] 378606K->36159
>> 6K(641944K) icms_dc=0 , 0.0034330 secs] [Times: user=0.02 sys=0.00,
>> real=0.00 secs]
>> 2011-02-28T22:53:04.956+0000: 263248.832: [GC 263248.832: [ParNew:
>> 19068K->2112K(19136K), 0.0029690 secs] 378552K->36163
>> 0K(641944K) icms_dc=0 , 0.0030460 secs] [Times: user=0.02 sys=0.00,
>> real=0.00 secs]
>> 2011-02-28T22:53:12.664+0000: 263256.540: [GC 263256.541: [ParNew:
>> 19136K->2112K(19136K), 0.0037690 secs] 378654K->36164
>> 7K(641944K) icms_dc=0 , 0.0038660 secs] [Times: user=0.01 sys=0.00,
>> real=0.01 secs]
>> 2011-02-28T22:53:20.608+0000: 263264.484: [GC 263264.484: [ParNew:
>> 19136K->1810K(19136K), 0.0032600 secs] 378671K->36134
>> 6K(641944K) icms_dc=0 , 0.0033470 secs] [Times: user=0.02 sys=0.00,
>> real=0.01 secs]
>> 2011-02-28T22:53:28.278+0000: 263272.154: [GC 263272.154: [ParNew:
>> 18834K->2112K(19136K), 0.0029870 secs] 378370K->36166
>> 1K(641944K) icms_dc=0 , 0.0030670 secs] [Times: user=0.01 sys=0.00,
>> real=0.01 secs]
>> 2011-02-28T22:53:35.919+0000: 263279.795: [GC 263279.795: [ParNew:
>> 19136K->1747K(19136K), 0.0037090 secs] 378685K->36129
>> 8K(641944K) icms_dc=0 , 0.0037920 secs] [Times: user=0.02 sys=0.00,
>> real=0.01 secs]
>> 11/02/28 22:53:36 INFO master.ServerManager: 9 region servers, 0 dead,
>> average load 760.2222222222222
>>
>>
>> On Mon, Feb 28, 2011 at 2:49 PM, Jean-Daniel Cryans <jdcryans@apache.org> wrote:
>>> Are you able to tell if that call in metaScanner is hanging or it's
>>> making multiple calls to the .META. region?
>>>
>>> If former, then jstack the region server that hosts .META. and see
>>> where it's blocked.
>>>
>>> if latter, then it means your .META. region is slow? Again, what's
>>> going on on the RS that hosts .META.?
>>>
>>> Finally, what's the master's log like during that time?
>>>
>>> J-D
>>>
>>> On Mon, Feb 28, 2011 at 2:41 PM, Nanheng Wu <nanhengwu@gmail.com> wrote:
>>>> J-D,
>>>>
>>>>  Thanks so much for your help so far! I sent disable commands on 4
>>>> rather small tables and they got stuck for a long time again, so I
>>>> took jstack of the master. From what I can tell, all disableTable
>>>> calls are blocked by a meta scanner thread (sample log below). At the
>>>> moment there were no other requests to the server at all. How should I
>>>> investigate this further? If it helps, here's some background: I have
>>>> several datasets, each of them is in a separate table; Our data
>>>> pipeline produces a new version of each dataset everyday and only the
>>>> lastest version should be used. This is how the data is loaded: for
>>>> each dataset 1) run a MR job and outputs HFiles 2) call loadTable.rb
>>>> to create a new table 3) disable and drop the previous version. As a
>>>> result some calls to load table and drop table would overlap. Please
>>>> let me know if something stands out to you as a potential culprit.
>>>> Thanks!
>>>>
>>>> BTW, I am running Hadoop 0.20.2 with HBase 0.20.6
>>>>
>>>> Thread 47 (IPC Server handler 13 on 60000):
>>>>  State: BLOCKED
>>>>  Blocked count: 3801
>>>>  Waited count: 72719
>>>>  Blocked on java.lang.Object@75ac522c
>>>>  Blocked by 27 (RegionManager.metaScanner)
>>>>  Stack:
>>>>    org.apache.hadoop.hbase.master.TableOperation.process(TableOperation.java:154)
>>>>    org.apache.hadoop.hbase.master.HMaster.disableTable(HMaster.java:842)
>>>>    sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
>>>>    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>>>>    java.lang.reflect.Method.invoke(Method.java:597)
>>>>    org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:657)
>>>>    org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:915)
>>>>
>>>>
>>>> Thread 27 (RegionManager.metaScanner):
>>>>  State: WAITING
>>>>  Blocked count: 1526058
>>>>  Waited count: 1488998
>>>>  Waiting on org.apache.hadoop.hbase.ipc.HBaseClient$Call@4dd44ab0
>>>>  Stack:
>>>>    java.lang.Object.wait(Native Method)
>>>>    java.lang.Object.wait(Object.java:485)
>>>>    org.apache.hadoop.hbase.ipc.HBaseClient.call(HBaseClient.java:722)
>>>>    org.apache.hadoop.hbase.ipc.HBaseRPC$Invoker.invoke(HBaseRPC.java:333)
>>>>    $Proxy1.get(Unknown Source)
>>>>    org.apache.hadoop.hbase.master.BaseScanner.checkAssigned(BaseScanner.java:543)
>>>>    org.apache.hadoop.hbase.master.BaseScanner.scanRegion(BaseScanner.java:192)
>>>>    org.apache.hadoop.hbase.master.MetaScanner.scanOneMetaRegion(MetaScanner.java:73)
>>>>    org.apache.hadoop.hbase.master.MetaScanner.maintenanceScan(MetaScanner.java:129)
>>>>    org.apache.hadoop.hbase.master.BaseScanner.chore(BaseScanner.java:153)
>>>>    org.apache.hadoop.hbase.Chore.run(Chore.java:68)
>>>>
>>>>
>>>>
>>>>
>>>> On Fri, Feb 25, 2011 at 10:23 AM, Jean-Daniel Cryans
>>>> <jdcryans@apache.org> wrote:
>>>>> An hour to disable? That doesn't sound right at all :)
>>>>>
>>>>> I would approach this problem like I generally do with HBase issue,
>>>>> first check the master log for any weirdness regarding my problem (in
>>>>> this case, grep for the table name).
>>>>>
>>>>> Then I would look the region server log(s) of the nodes that were
>>>>> hosting regions from that table. You should see the steps taken to
>>>>> disable the regions (starting to close, flush, region completely
>>>>> closed).
>>>>>
>>>>> If you are able to do it while it's taking a very long time to
>>>>> disable, try to jstack the process the seems to be hanging.
>>>>>
>>>>> Finally, like I said in another thread, there's a bug in 0.20.6 that
>>>>> almost prevent disabling a table (or re-enabling) if any region
>>>>> recently split and the parent wasn't cleaned yet from .META. and that
>>>>> is fixed in 0.90.1
>>>>>
>>>>> J-D
>>>>>
>>>>> On Thu, Feb 24, 2011 at 11:37 PM, Nanheng Wu <nanhengwu@gmail.com>
wrote:
>>>>>> I think you are right, maybe in the long run I need to re-architect
my
>>>>>> system so that it doesn't need to create new and delete old tables
all
>>>>>> the time. In the short term I am having a really hard time with the
>>>>>> disabling function, I ran a disable command on a very small table
>>>>>> (probably dozen of MBs in size) and are no client using the cluster
at
>>>>>> all, and that took about 1 hour to complete! The weird thing is on
the
>>>>>> web UI only the region server carrying the META table has non-zero
>>>>>> requests, all other RS have 0 requests the entire time. I would think
>>>>>> they should get some request to flush the memstore at least. I *am*
>>>>>> using the same RS nodes for some map reduce job at the time and top
>>>>>> shows the memory usage is almost full on the META region. Would you
>>>>>> have some idea of what I should investigate?
>>>>>> Thanks so much.
>>>>>
>>>>
>>>
>>
>

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