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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: Write Operations on a Table Hangs
Date Thu, 28 Apr 2011 22:05:32 GMT
Yes, there are pauses around splits, and it's getting better with
newer versions (0.20 is old). In 0.90 you can pre-split the tables
when importing huge datasets
http://hbase.apache.org/book/important_configurations.html#disable.splitting

You could try jstack'ing the region servers to figure where it's
stuck, but unless you are using a 0.20 that's older than 0.20.6 the
probability of getting a dead lock is extremely low. Please use this
guide to debug HBase issues: http://hbase.apache.org/book/trouble.html

EC2 might be another issue by itself.

J-D

On Thu, Apr 28, 2011 at 2:59 PM, Harold Lim <rold_50@yahoo.com> wrote:
> Hi J-D,
>
> What I notice is that, when a region server is going to split the region (create more
regions), the write operations kind of paused, and then after a few seconds, the write operations
of my program will continue.
>
> However, there are cases where the write operations does not work anymore. I go to the
hbase shell and try to do some operations on the table and it does not work too.  Operations
on other table still seem to work fine.
>
>
> I'm using HBase 0.20.x (manually compiled). It's a 10 node cluster on EC2. No special
configurations.
>
>
> Thanks,
> Harold
>
>
>
> --- On Thu, 4/28/11, Jean-Daniel Cryans <jdcryans@apache.org> wrote:
>
>> From: Jean-Daniel Cryans <jdcryans@apache.org>
>> Subject: Re: Write Operations on a Table Hangs
>> To: user@hbase.apache.org
>> Date: Thursday, April 28, 2011, 4:55 PM
>> That message only means that the
>> region is being flushed before it's closed.
>>
>> When you say you can't write to it anymore, you mean at the
>> moment of
>> writing or if you let it alone for a few minutes and then
>> come back
>> would you be able to?
>>
>> It's not a behavior that I remember seeing, it might just
>> be your
>> description that's different. In any case, I've never seen
>> disabling a
>> table really doing any good.
>>
>> And which HBase version is that? What kind of cluster? Any
>> special
>> configuration? Anything about "blocking" in the logs?
>>
>> Thx,
>>
>> J-D
>>
>> On Thu, Apr 28, 2011 at 12:52 PM, Harold Lim <rold_50@yahoo.com>
>> wrote:
>> > Hi All,
>> >
>> > Sometimes when I try to write to a table (I have a
>> program that writes lots of rows to an hbase table), it
>> hangs and then I can't write to the table anymore.
>> > When I look at a region server's log, I see the
>> message
>> > 13:49:59,945 DEBUG
>> org.apache.hadoop.hbase.regionserver.HRegion: waiting for
>> cache flush to complete for region usertable
>> >
>> > I try to disable/drop the table using the hbase shell
>> but it keeps saying that the table is not disabled.
>> >
>> > Any idea what's causing this?
>> >
>> > Thanks,
>> > Harold
>> >
>> >
>>
>

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