mysql-proxy CPU usage spikes to 100% for no particular reason

[Rafal Pasek]

Hello,

I am having a problem with mysql-proxy (0.8.0) sometimes spiking up to 100% CPU usage for a few minutes and then getting back to normal.

My config is RHEL5.3 x64 with Apache and mysql-proxy setup to use two MySQL DB backends configured. The backends are configured to do Master-Master replication for the reason of automatic failover in case one of the DBs is down. The lua script in use is just as follows:
------------------------------------------
function connect_server()
proxy.connection.backend_ndx = 1
end

function read_query(packet)
proxy.connection.backend_ndx = 1
end
------------------------------------------

The Apache gets >100req/sec with digest authentication in use (this is where DB connection is used). Usually there are no problems but sometimes (less than once/24h) we observe that CPU usage of mysql-proxy rises to 99.9% for a time usually about 5 minutes. Afterwards it drops down to the usual 0.1% and everything is back to normal. At the same time there is no increase in Apache's CPU usage.

Is there someone else experiencing a similar behavior?
Is there any other easy way to get a failover behavior for MySQL DBs, but without mysql-proxy?