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From Roshan Dawrani <roshandawr...@gmail.com>
Subject Re: mutator.execute() timings - big variance noted - pointers needed on understanding/improving it
Date Fri, 11 Mar 2011 02:04:02 GMT
Hi All,

Thanks for the inputs. I will start investigating this morning with the help
of these.

Regards,
Roshan

On Fri, Mar 11, 2011 at 2:49 AM, aaron morton <aaron@thelastpickle.com>wrote:

> http://wiki.apache.org/cassandra/FAQ#slows_down_after_lotso_inserts
>
> <http://wiki.apache.org/cassandra/FAQ#slows_down_after_lotso_inserts>Aaron
>
> On 11 Mar 2011, at 05:08, sridhar basam wrote:
>
>
> Sounds like GC from your description of fast->slow->fast. Collect GC times
> from both the client and server side and plot against your application
> timing.
>
>  If you uncomment the verbose GC entries in the cassandra-env.sh file you
> should get timing for the server side, pass in the same arguments for your
> client. Align time across the 3 files and plot to see if GC is the cause.
>
>  Sridhar
>
>
>
> On Thu, Mar 10, 2011 at 9:30 AM, Roshan Dawrani <roshandawrani@gmail.com>wrote:
>
>> Hi,
>>
>> I am in the middle of some load testing on a 1-node Cassandra setup. We
>> are not on very high loads yet. We have recorded the timings taken up by
>> mutator.execute() calls and we see this kind of variation during the test
>> run:
>>
>> So, 25% of the times, execute() calls come back in 25 milli-seconds, but
>> the longer calls go upto 4 seconds.
>>
>> Can someone please provide some pointers on what and where to focus on in
>> my Hector / Cassandra setup? We are mostly on the default Cassandra
>> configuration at this time - only change is the max connection pool size
>> (CassandraHostConfigurator.maxActive) is changed to 300 from a default of
>> 50.
>>
>> I would also like to add that the time increase is not linear - it starts
>> fast, goes, slow, very slow, and becomes faster again.
>>
>> ------------------------
>>   25%     29
>>   50%    105
>>   66%    185
>>   70%    208
>>   75%    240
>>   80%    297
>>   90%    510
>>   95%    854
>>   98%   1075
>>   99%   1215
>>  100%   4442
>> ------------------------
>>
>> --
>> Roshan
>> Blog: http://roshandawrani.wordpress.com/
>> Twitter: @roshandawrani <http://twitter.com/roshandawrani>
>> Skype: roshandawrani
>>
>>
>
>

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