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From Илья Шипицин <chipits...@gmail.com>
Subject Re: performance is drastically degraded after 0.7.8 --> 1.0.11 upgrade
Date Tue, 04 Sep 2012 12:27:42 GMT
it was good idea to have a look at StorageProxy :-)


1.0.10 Performance Tests
StorageProxy

RangeOperations: 546
ReadOperations: 694563
TotalHints: 0
TotalRangeLatencyMicros: 4469484
TotalReadLatencyMicros:245669679
TotalWriteLatencyMicros: 57819722
WriteOperations:208741


0.7.10 Performance Tests
StorageProxy

RangeOperations: 520
ReadOperations: 671476
TotalRangeLatencyMicros: 2208902
TotalReadLatencyMicros: 162186009
TotalWriteLatencyMicros: 33911222
WriteOperations: 204806


2012/9/3 aaron morton <aaron@thelastpickle.com>

> The whole test run is taking longer ? So it could be slower queries or
> slower test setup / tear down?
>
> If you are creating and truncate the KS for each of the 500 tests is that
> taking longer ? (Schema code has changed a lot 0.7 > 1.0)
> Can you log the execution time for tests and find ones that are taking
> longer ?
>
> There are full request metrics available on the StorageProxy JMX object.
>
> Cheers
>
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 31/08/2012, at 4:45 PM, Илья Шипицин <chipitsine@gmail.com> wrote:
>
> we are using functional tests ( ~500 tests in time).
> it is hard to tell which query is slower, it is "slower in general".
>
> same hardware. 1 node, 32Gb RAM, 8Gb heap. default cassandra settings.
> as we are talking about functional tests, so we recreate KS just before
> tests are run.
>
> I do not know how to record queries (there are a lot of them), if you are
> interested, I can set up a special stand for you.
>
> 2012/8/31 aaron morton <aaron@thelastpickle.com>
>
>> we are running somewhat queue-like with aggressive write-read patterns.
>>
>> We'll need some more details...
>>
>> How much data ?
>> How many machines ?
>> What is the machine spec ?
>> How many clients ?
>> Is there an example of a slow request ?
>> How are you measuring that it's slow ?
>> Is there anything unusual in the log ?
>>
>> Cheers
>>
>>  -----------------
>> Aaron Morton
>> Freelance Developer
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 31/08/2012, at 3:30 AM, Edward Capriolo <edlinuxguru@gmail.com> wrote:
>>
>> If you move from 7.X to 0.8X or 1.0X you have to rebuild sstables as
>> soon as possible. If you have large bloomfilters you can hit a bug
>> where the bloom filters will not work properly.
>>
>>
>> On Thu, Aug 30, 2012 at 9:44 AM, Илья Шипицин <chipitsine@gmail.com>
>> wrote:
>>
>> we are running somewhat queue-like with aggressive write-read patterns.
>> I was looking for scripting queries from live Cassandra installation, but
>> I
>> didn't find any.
>>
>> is there something like thrift-proxy or other query logging/scripting
>> engine
>> ?
>>
>> 2012/8/30 aaron morton <aaron@thelastpickle.com>
>>
>>
>> in terms of our high-rate write load cassandra1.0.11 is about 3 (three!!)
>> times slower than cassandra-0.7.8
>>
>> We've not had any reports of a performance drop off. All tests so far have
>> show improvements in both read and write performance.
>>
>> I agree, such digests save some network IO, but they seem to be very bad
>> in terms of CPU and disk IO.
>>
>> The sha1 is created so we can diagnose corruptions in the -Data component
>> of the SSTables. They are not used to save network IO.
>> It is calculated while streaming the Memtable to disk so has no impact on
>> disk IO. While not the fasted algorithm I would assume it's CPU overhead
>> in
>> this case is minimal.
>>
>> there's already relatively small Bloom filter file, which can be used for
>> saving network traffic instead of sha1 digest.
>>
>> Bloom filters are used to test if a row key may exist in an SSTable.
>>
>> any explanation ?
>>
>> If you can provide some more information on your use case we may be able
>> to help.
>>
>> Cheers
>>
>>
>> -----------------
>> Aaron Morton
>> Freelance Developer
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 30/08/2012, at 5:18 AM, Илья Шипицин <chipitsine@gmail.com> wrote:
>>
>> in terms of our high-rate write load cassandra1.0.11 is about 3 (three!!)
>> times slower than cassandra-0.7.8
>> after some investigation carried out I noticed files with "sha1" extension
>> (which are missing for Cassandra-0.7.8)
>>
>> in maybeWriteDigest() function I see no option fot switching sha1 digests
>> off.
>>
>> I agree, such digests save some network IO, but they seem to be very bad
>> in terms of CPU and disk IO.
>> why to use one more digest (which have to be calculated), there's already
>> relatively small Bloom filter file, which can be used for saving network
>> traffic instead of sha1 digest.
>>
>> any explanation ?
>>
>> Ilya Shipitsin
>>
>>
>>
>>
>>
>
>

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