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From Nate McCall <n...@thelastpickle.com>
Subject Re: High CPU usage with authentication enabled
Date Wed, 21 Aug 2013 18:46:36 GMT
The bcrypt rounds are indeed expensive and ClientState should hold the
result for the active connection. So it sounds like you are creating a lot
of new connections and thus hitting that bcrypt penalty.


On Wed, Aug 21, 2013 at 12:28 PM, Joshua M. Thompson <
joshua.thompson@gmail.com> wrote:

> Hello,
>
> I've been tasked with tuning a Cassandra-based app for eventual production
> deployment and I'm running into an issue I can't seem to solve when I run
> my load tests. I'm still relatively new to Cassandra so i'm hoping there is
> something obvious I'm missing here.
>
> Basically, everything runs great as long as authentication is disabled
> (using the AllowAll* modules.) In that configuration CPU usage on the
> application servers and the Cassandra servers is minimal. But as soon as
> enable authentication the CPU usage on the Cassandra nodes shoots up to
> around 150% on all nodes, and any requests to the application that make
> Cassandra calls have an increase in response time of ~500 ms. Application
> server load remains unchanged, however.
>
> The application is a PHP app using phpcassa, and running under PHP-FPM.
> Connection pooling is turned on, but being a PHP app this only goes so far.
> There are three Cassandra nodes running 1.2.8, on 8-CPU, 16 GB ESX
> instances. Each node is on a different ESX host.
>
> By every metric I have checked the actual read/write response time on the
> cluster is very fast; it's just the authentication that seems to bog things
> down. Is logging into a Cassandra instance really that CPU intensive?
>

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