On Wed, 3 Nov 2010, Paul Graydon wrote: > I'm facing an interesting challenge at the moment. Our Apache httpd > based load balancers are starting to show signs of strain. Nothing too > bad but a good indicator that as the amount of traffic to our sites > increases there will come a point when they can't cope. I've been > expecting this but at the moment as a "Standalone" sysadmin I've got too > much on my plate to even get on to anything pro-active that requires > more than a few hours work.. with inevitable consequences, though I'm > making favourable progress. Load is now reaching a stage where it's > spawning enough httpd sessions to be of some concern and at a level that > seems to be resulting in latency for requests.
a couple quick comments 1. Nginx is single-threaded, so while it's screaming fast, it won't use more than one core. 2. If you are doing a lot of SSL operations, consider adding a SSL accelerator card, that can effectivly eliminate the overhead of SSL. 3. how tuned is your apache instance? I've seen 10x performance improvements by doing things like compiling the modules I need in (instead of using .so modules) and not loading any modules that I don't need. Combined with newer hardware (two sockets will get you 12 cores nowdays), you could easily scale quite a bit from your existing capibilities without having to take the risk of changing technologies. apache is pretty inefficient in how it logs, try logging to a ramdisk and see if that makes any difference. check what you have set for your ssl session cache, if it's not in shared memory, move it there (the overhead of filesystem operations for shared disk, even if you almost always operate in ram disk buffers, can be noticable at high traffic levels Definantly measure where your latency is happening. It could be that apache is the problem, but it could also be that you are running into something else. how many processes are you seeing that is making you concerned? David Lang _______________________________________________ Tech mailing list [email protected] http://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
