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From "Joshua M. Thompson" <>
Subject High CPU usage with authentication enabled
Date Wed, 21 Aug 2013 17:28:23 GMT

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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