I recently resolved a server performance issue. Here’s a recap of what I went through in hopes you find it useful. I’m running Ubuntu on the smallest Rackspace Cloud Server available (too much foreshadow?). The server has 256MB of ram and it’s sole purpose is to run Drupal on Apache. I have set up a few servers in the past, but I do not claim to be an expert. This recent problem had me stumped for a while.
The Symptoms
Soon after Apache was started (or restarted), all was well. Over time the server would continue to grow slower. When the server was most bogged down, running “free -m” would show that all of the swap was in use. Running “ps aux —sort -rss” revealed that all of the memory was, in fact, being used by Apache.
This bit of information didn’t strike me as very valuable since I was hoping to just shut down whatever was using all of the memory. If any other service was using all of the memory I’d shut it down… but Apache is the whole reason the site is up. The fact that the server seemed fine at first, then got progressively worse, made me think memory leak. I was wrong.
The Resolution
Reluctantly, I opened a chat with support. I assumed the chat would be a waste of time (based on previous experiences with other hosting providers I have dealt with in the past). I assumed that I would get a response to the effect of: “There are too many variables in a server for us to trouble shoot this issue. Might I suggest our more expensive option?” This was not my experience.
Jordan C. shot me a handful of links to posts where people outlined ways they needed to reconfigure Apache for running on less than 512MB. I did not realize that 256MB was frugal enough to require special configuration. Since I have never set up a server with less than 512MB of ram, I’ve never needed to fuss much with the default configuration of Apache. I was used to Apache just working.
The links that proved most helpful for me were on shortens.net and vpslink.com. After sniffing around the internet and a little trial & error this is the bit of configuration that ultimately fixed my particular issue.
<IfModule mpm_prefork_module>
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxClients 100
MaxRequestsPerChild 500
</IfModule>
While “fanatical” sounds a little strong, it’s not his job to help me configure Apache. Jordan didn’t provide a lot of trouble shooting, but the links he provided nudged me in the right direction. Before following these links I was in the frustrating position of not even knowing enough to ask (or google) the right questions. Now, I can get back to making things.