Help needed with event MPM configuration

[Rajalakshmi Iyer <raj@xxxxxxxxxxxxx>]

Hello,

I need some assistance with tuning Apache with event MPM.

The Apache server in consideration is running an application module. The current MPM settings are -

<IfModule mpm_event_module>
    StartServers             2
    ServerLimit              4
    MinSpareThreads         60
    MaxSpareThreads         240
    MaxClients              240
    ThreadsPerChild         60
    MaxRequestWorkers       240
    MaxConnectionsPerChild   0
    MaxRequestsPerChild      0
</IfModule>

This means that there are 240 threads available to work on 240 established connections.

The AsyncRequestWorkerFactor for event MPM is 2 by default.

So, based on http://httpd.apache.org/docs/current/mod/event.html, the server can accept at the most (AsyncRequestWorkerFactor + 1) * MaxRequestWorkers, i.e. 720 maximum concurrent connections.

The process will accept new connections only when current number of connections is lower than ThreadsPerChild + (AsyncRequestWorkerFactor * number of idle workers)

 

Assuming the server is always under heavy load, the 240 worker threads are busy working on 240 requests from 240 established connections. As soon as they finish their work, they will be working on the subsequent requests on the same connection.

There are 720 connections that have been accepted by the server, but only 240 of those have been worked upon. The remaining 480 will never get a chance, because there are subsequent requests on the same connection to be worked upon.

As it stands today, the symptoms observed are --

1. The server is not responding to new connections
2. The 8 core server machine shows that 80% of each of the 8 cores is idle, which means that the workers are not really doing much. Does that mean that each of the 240 threads when allocated a connection is waiting for requests on that connection and not picking up other connections that are newly established?
   

Any help around what settings can be modified to alleviate these symptoms would be useful.

Thanks
Raj

@BlisMedia

www.blismedia.com

This email and any attachments to it may be confidential and are intended solely for the use of the individual to whom it is addressed. Any views or opinions expressed are solely those of the author and do not necessarily represent those of BlisMedia Ltd, a company registered in England and Wales with registered number 06455773. Its registered office is 3rd Floor, 101 New Cavendish St, London, W1W 6XH, United Kingdom.

If you are not the intended recipient of this email, you must neither take any action based upon its contents, nor copy or show it to anyone. Please contact the sender if you believe you have received this email in error.