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?
