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From Sameer Farooqui <cassandral...@gmail.com>
Subject Re: Problems with Python Stress Test
Date Fri, 04 Feb 2011 23:23:10 GMT
Brandon,

Thanks for the response. I have also noticed that stress.py's progress
interval gets thrown off in low memory situations.

What did you mean by "contrib/stress on 0.7 instead".  I don't see that dir
in the src version of 0.7.

- Sameer


On Thu, Feb 3, 2011 at 5:22 PM, Brandon Williams <driftx@gmail.com> wrote:

> On Thu, Feb 3, 2011 at 7:02 PM, Sameer Farooqui <cassandralabs@gmail.com>wrote:
>
>> Hi guys,
>>
>> I was playing around with the stress.py test this week and noticed a few
>> things.
>>
>> 1) Progress-interval does not always work correctly. I set it to 5 in the
>> example below, but am instead getting varying intervals:
>>
>
> Generally indicates that the client machine is being overloaded in my
> experience.
>
> 2) The key_rate and op_rate doesn't seem to be calculated correctly. Also,
>> what is the difference between the interval_key_rate and the
>> interval_op_rate? For example in the example above, the first row shows 6662
>> keys inserted in 5 seconds and 6662 / 5 = 1332, which matches the
>> interval_op_rate.
>>
>
> There should be no difference unless you're doing range slices, but IPC
> timing makes them vary somewhat.
>
> 3) If I write x KB to Cassandra with py_stress, the used disk space doesn't
>> grow by x after the test. In the example below I tried to write 500,000 keys
>> * 32 bytes * 5 columns = 78,125 kilobytes of data to the database. When I
>> checked the amount of disk space used after the test it actually grew by
>> 2,684,920 - 2,515,864 = 169,056 kilobytes. Is this because perhaps the
>> commit log got duplicate copies of the data as the SSTables?
>>
>
> Commitlogs could be part of it, you're not factoring in the column names,
> and then there's index and bloom filter overhead.
>
> Use contrib/stress on 0.7 instead.
>
> -Brandon
>

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