vBulletin Process spikes causing errors

[5starpool]

My forum is hosted on a hostgator shared server, and has a process limit of 25 concurrent processes. Most of the time there is no issue, and between 2-4 processes are running at a time. Occasionally though, the processes will spike, causing error 500, and making the site unavailable. Here is a sample list of processes running at a time when my site is unavailable.

32572 /usr/local/cpanel/cpanel ./frontend/x3/hg/processes.php 0% 0.1% Kill Process
32185 /usr/bin/php/home/cpname/public_html/forum/editpost.php 0% 0.1% Kill Process
32169 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
32099 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31900 /usr/bin/php/home/cpname/public_html/forum/editpost.php 0% 0.1% Kill Process
31881 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31846 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31839 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31702 /usr/bin/php/home/cpname/public_html/forum/forumdisplay.php 0% 0.1% Kill Process
31546 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31534 /usr/bin/php/home/cpname/public_html/forum/post_thanks.php 0% 0.1% Kill Process
31506 /usr/bin/php/home/cpname/public_html/forum/showthread.php 0.1% 0.1% Kill Process
31445 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31296 /usr/bin/php/home/cpname/public_html/forum/misc.php 0% 0.1% Kill Process
32178 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31728 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31647 /usr/bin/php/home/cpname/public_html/forum/forumdisplay.php 0% 0.1% Kill Process
31636 /usr/bin/php/home/cpname/public_html/forum/ajax.php 0% 0.1% Kill Process
31538 /usr/bin/php/home/cpname/public_html/forum/index.php 0% 0.1% Kill Process
31380 /usr/bin/php/home/cpname/public_html/forum/showthread.php 0.1% 0.1% Kill Process
31300 /usr/bin/php/home/cpname/public_html/forum/misc.php 0% 0.1% Kill Process
31297 /usr/bin/php/home/cpname/public_html/forum/misc.php 0% 0.1% Kill Process
31229 /usr/bin/php/home/cpname/public_html/forum/showthread.php 0% 0.1% Kill Process
29553 /usr/bin/php/home/cpname/public_html/forum/misc.php 0% 0.1% Kill Process
27105 /usr/bin/php/home/cpname/public_html/forum/misc.php 0% 0.1% Kill Process

As you can see, most of these are standard vbulletin php files that would be accessed thousands of times a day, and I would imagine would only last a fraction of a second usually, but only occasionally does it spike. This is not caused by a surge in users, as it is pretty constant usage at around 80-140 users for most of the day (the rest is quieter). I have run the vB optimisation things mentioned in this page :http://www.vbulletin-faq.com/optimize-vbulletin-server.htm but it still occurs intermittently, and I have no idea why. I have talked this over with live support on hostgator and they are adamant that it is nothing on their side that is causing this.

Could it be caused by vb hacks I've installed? I haven't installed any over the last few months that I can remember, and this has mostly been happening the last 2-3 months. My forum is about 17 months old and has around 340k posts. There is also one very large thread of 150k posts. Could this have anything to do with the issue?

I am at a loss here I'm afraid, so any help would be greatly appreciated.

[5starpool]

Has no one got any suggestions? Is there a better palce to post to ask about this?

[Lynne]

Probably a better place to ask about server issues is over in the Server Configuration forum on vbulletin.com

[Videx]

Actually, I think Lynne missed the part about this being a shared server. In fact you have no control over the server at all so don't bother going to the server configuration forum.

You haven't made it clear how many concurrent users you average, which is all that counts. The new default timeout in mysql 5 is a measly 20 seconds, which could be the whole problem. I know our host refuses to raise that limit to the recommended 180 or so.

My own year or so on Hostgator with sometimes as many as FIVE concurrent users on a shared server would often lead to server errors. Tech support always said everything was working normally.

[5starpool]

Actually, I think Lynne missed the part about this being a shared server. In fact you have no control over the server at all so don't bother going to the server configuration forum.

You haven't made it clear how many concurrent users you average, which is all that counts. The new default timeout in mysql 5 is a measly 20 seconds, which could be the whole problem. I know our host refuses to raise that limit to the recommended 180 or so.

My own year or so on Hostgator with sometimes as many as FIVE concurrent users on a shared server would often lead to server errors. Tech support always said everything was working normally.

Usually 80-140 online for most of the day. If I thought that VPS would certainly solve this issue, I'd be prepared to take the financial hit, but don't want to do this, and then find that it is an unrelated issue that still causes problems post move.

[Videx]

Sorry for not being more specific. Are you talking 80-140 concurrent members doing things. or Guests & Searchbots?

If you have more than 30 active members on simultaneously on a regular basis you need VPS these days. Hosts have oversold a lot of the shared servers. But you should be able to peak to 100 on a decent shared server.

[5starpool]

Ya, If there are 100 showing as online, about 55 would be logged in members, the rest guests and bots. I know we do have a good few lurkers as well, so I'd imagine that the majority of the rest would be real people clicking things.

Sounds like by your criteria above I'd definitely need to move. I appreciate the input.

[radiofranky]

I'm having the same issue with dreamhost.com with only 1 user trying to load the WYSWYG editor. This is also on a shared host

[BirdOPrey5]

Sorry for not being more specific. Are you talking 80-140 concurrent members doing things. or Guests & Searchbots?

If you have more than 30 active members on simultaneously on a regular basis you need VPS these days. Hosts have oversold a lot of the shared servers. But you should be able to peak to 100 on a decent shared server.

That's just not true. You can definitely be fine on a quality shared server- but Hostgator is not a quality shared server. I have 100+ active members at time (and have had 150+ in the past) on shared without issue.

[radiofranky]

That's just not true. You can definitely be fine on a quality shared server- but Hostgator is not a quality shared server. I have 100+ active members at time (and have had 150+ in the past) on shared without issue.

which shared host are you on?

thanks

[BirdOPrey5]

I use URLJet.

[radiofranky]

I use URLJet.

kind of expensive. I'm paying $30 VSP with 1G ram and 50G disk space but is in Sweden. :)

[Videx]

Ya, it's a bit disingenuous to talk about good "shared" hosting at $25USD/month when VPS packages usually start at about $30USD/month.

But to be fair, VPS is really just "less shared" hosting - you're still sharing a cpu with someone else.