incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Илья Шипицин <chipits...@gmail.com>
Subject Re: performance is drastically degraded after 0.7.8 --> 1.0.11 upgrade
Date Fri, 31 Aug 2012 04:45:14 GMT
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
>
>
>
>
>

Mime
View raw message