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From Suraj Varma <svarma...@gmail.com>
Subject Re: more regionservers does not improve performance
Date Fri, 12 Oct 2012 07:34:37 GMT
What have you configured your hbase.hstore.blockingStoreFiles and
hbase.hregion.memstore.block.multiplier? Both of these block updates
when the limit is hit. Try increasing these to say 20 and 4 from the
default 7 and 2 and see if it helps.

If this still doesn't help, see if you can set up ganglia to get a
better insight into what is bottlenecking.
--Suraj



On Thu, Oct 11, 2012 at 11:47 PM, Pankaj Misra
<pankaj.misra@impetus.co.in> wrote:
> OK, Looks like I missed out reading that part in your original mail. Did you try some
of the compaction tweaks and configurations as explained in the following link for your data?
> http://hbase.apache.org/book/regions.arch.html#compaction
>
>
> Also, how much data are your putting into the regions, and how big is one region at the
end of data ingestion?
>
> Thanks and Regards
> Pankaj Misra
>
> -----Original Message-----
> From: Jonathan Bishop [mailto:jbishop.rwc@gmail.com]
> Sent: Friday, October 12, 2012 12:04 PM
> To: user@hbase.apache.org
> Subject: RE: more regionservers does not improve performance
>
> Pankaj,
>
> Thanks  for the reply.
>
> Actually, I am using MD5 hashing to evenly spread the keys among the splits, so I don’t
believe there is any hotspot. In fact, when I monitory the web UI for HBase I see a very even
load on all the regionservers.
>
> Jon
>
> Sent from my Windows 8 PC <http://windows.microsoft.com/consumer-preview>
>
>  *From:* Pankaj Misra <pankaj.misra@impetus.co.in>
> *Sent:* Thursday, October 11, 2012 8:24:32 PM
> *To:* user@hbase.apache.org
> *Subject:* RE: more regionservers does not improve performance
>
> Hi Jonathan,
>
> What seems to me is that, while doing the split across all 40 mappers, the keys are not
randomized enough to leverage multiple regions and the pre-split strategy. This may be happening
because all the 40 mappers may be trying to write onto a single region for sometime, making
it a HOT region,  till the key falls into another region, and then the other region becomes
a HOT region hence you may seeing a high impact of compaction cycles reducing your throughput.
>
> Are the keys incremental? Are the keys randomized enough across the splits?
>
> Ideally when all 40 mappers are running you should see all the regions being filled up
in parallel for maximum throughput. Hope it helps.
>
> Thanks and Regards
> Pankaj Misra
>
>
> ________________________________________
> From: Jonathan Bishop [jbishop.rwc@gmail.com]
> Sent: Friday, October 12, 2012 5:38 AM
> To: user@hbase.apache.org
> Subject: more regionservers does not improve performance
>
> Hi,
>
> I am running a MR job with 40 simultaneous mappers, each of which does puts to HBase.
I have ganged up the puts into groups of 1000 (this seems to help quite a bit) and also made
sure that the table is pre-split into 100 regions, and that the row keys are randomized using
MD5 hashing.
>
> My cluster size is 10, and I am allowing 4 mappers per tasktracker.
>
> In my MR job I know that the mappers are able to generate puts much faster than the puts
can be handled in hbase. In other words if I let the mappers run without doing hbase puts
then everything scales as you would expect with the number of mappers created. It is the hbase
puts which seem to be the bottleneck.
>
> What is strange is that I do not get much run time improvement by increasing the number
regionservers beyond about 4. Indeed, it seems that the system runs slower with 8 regionservers
than with 4.
>
> I have added the following in hbase-env.sh hoping this would help... (from the book HBase
in Action)
>
> export HBASE_OPTS="-Xmx8g"
> export HBASE_REGIONSERVER_OPTS="-Xmx8g -Xms8g -Xmn128m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC
-XX:CMSInitiatingOccupancyFraction=70"
>
> # Uncomment below to enable java garbage collection logging in the .out file.
> export HBASE_OPTS="${HBASE_OPTS} -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCDateStamps
-Xloggc:${HBASE_HOME}/logs/gc-hbase.log"
>
> Monitoring hbase through the web ui I see that there are pauses for flushing, which seems
to run pretty quickly, and for compacting, which seems to take somewhat longer.
>
> Any advice for making this run faster would be greatly appreciated.
> Currently I am looking into installing Ganglia to better monitory my cluster, but yet
to have that running.
>
> I suspect an I/O issue as the regionservers do not seem terribly loaded.
>
> Thanks,
>
> Jon
>
> ________________________________
>
> Impetus Ranked in the Top 50 India’s Best Companies to Work For 2012.
>
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>
>
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>
> ________________________________
>
> Impetus Ranked in the Top 50 India’s Best Companies to Work For 2012.
>
> Impetus webcast ‘Designing a Test Automation Framework for Multi-vendor Interoperable
Systems’ available at http://lf1.me/0E/.
>
>
> NOTE: This message may contain information that is confidential, proprietary, privileged
or otherwise protected by law. The message is intended solely for the named addressee. If
received in error, please destroy and notify the sender. Any use of this email is prohibited
when received in error. Impetus does not represent, warrant and/or guarantee, that the integrity
of this communication has been maintained nor that the communication is free of errors, virus,
interception or interference.

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