Home/ Questions/Q 5982733
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-22T22:07:45+00:00

I have a LAMP server (Quad Core Debian with 4GB RAM, Apache 2.2 and

  • 0

I have a LAMP server (Quad Core Debian with 4GB RAM, Apache 2.2 and PHP 5.3) with Rackspace which is used as an API Server. I would like to know what is the best KeepAlive option for Apache given our setup.

  • The API server hosts a single PHP file which responds with plain JSON. This is a fairly hefty file which performs some MySql reads/writes and quite a few Memcache lookups.
  • We have about 90 clients that are logged into the system at any one time.
  • Roughly 1/3rd of clients would be idle.
  • Of the active clients (roughly 60) they send a request to the API every 3 seconds.
  • Clients switch from active to idle and vice versa every 15 or 20 minutes or so.

With KeepAlive On, the server goes nuts and memory peaks at close to 4GB (swap is engaged etc).
With KeepAlive Off, the memory sits at 3GB however I notice that Apache is constantly killing and creating new processes to handle each connection.

So, my three options are:

  1. KeepAlive On and KeepAliveTimeout Default – In this case I guess I will just need to get more RAM.

  2. KeepAlive On and KeepAliveTimeout Low (perhaps 10 seconds?) If KeepAliveTimeout is set at 10 seconds, will a client maintain a constant connection to that one process by accessing the resource at regular 3 second intervals? When that client becomes idle for longer than 10 seconds will the process then be killed? If so I guess option 2 looks like the best one to go for?

  3. KeepAlive Off This is clearly best for RAM, but will it have an impact on the response times due to the work involved in setting up a new process for each request?

Which option is best?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Instead of managing the KeepAlive settings, which clearly have no real advantage in your particular situation between the 3 options, you should consider switching the Apache to an event or a thread based MPM where you could easily use KeepAlive On and set the Timeout value high.

    I would go as far as also considering the switch to Apache on Windows. The benefit here is that it’s MPM is completely thread based and takes advantage of Windows preference for threads over processes. You can easily do 512 threads with KeepAlive On and Timeout of 3-10 seconds on 1-2GB of RAM.

    WampDeveloper Pro –
    Xampp –
    WampServer

    Otherwise, your only other options are to switch MPM from Prefork to Worker…
    http://httpd.apache.org/docs/2.2/mod/worker.html

    Or to Event (which also got better with Apache 2.4)…
    http://httpd.apache.org/docs/2.2/mod/event.html

    • 0