Re: [MediaWiki-l] Apache going nuts and eating all memory

As OQ mentioned, if your MaxClients in Apache is set too high when you get a burst of connections like this you'll eat up all your RAM and begin swapping which kills performance real quick. If you don't want it to fail in this way you can tune your MaxClients to a point where even with a burst you don't use up all your RAM at the expense of dropping/refusing connections. As a rough guess at what to set MaxClients to use "top" and look at the difference between the RES and SHR columns of all httpd processes. I believe this is roughly the amount of non-shared memory each of the child Apache processes are using (for example, I'm averaging 10 MB per process). Take the maximum amount of RAM you want Apache to use and divide it by this memory to get a rough number for MaxClients. You can monitor memory usage and adjust this as needed or through load testing. Of course, this is a solution to the usage of swap and not the actual issue you are having. I would continue to look at what is causing the surge in requests. Is it a DoS of some sort (either accidental or on purpose) or is some part of the server stalling which is causing requests to pile up and overflow? For example, if the database is having an issue (a bunch of long queries) then all Apache requests will start piling up until you hit swap or the database issue resolves itself. Along these lines I would suggest some sort of monitoring/logging service like Zabbix or Nagois (to name just two, there are many similar options to choose from). This helps you on two fronts: 1) Logging of Parameters and 2) Service Monitoring. Trying to diagnose issues after the fact can be difficult/impossible and with such a service you have a record of many things to help you pinpoint, or at least narrow down, the root cause of the issue. Monitoring is also invaluable as you can be emailed/texted when the issue actually happens (or is just starting) rather than 5 minutes after the website has begun timing out for everyone. On 29 October 2012 19:14, David Gerard <dgerard(a)gmail.com> wrote: -- Dave Humphrey -- dave(a)uesp.net Founder/Server Admin of the Unofficial Elder Scrolls Pages -- www.uesp.net