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Apache Crashing Due to Memory Limit Being Reached On VPS

Posted By: doug

Apache Crashing Due to Memory Limit Being Reached On VPS - 05/25/08 07:44 PM

I just moved to a new VPS which on paper is better than my old VPS - faster processor, more RAM, more bandwidth, etc. - but I have just discovered it all means nothing.

Apparently the only thing that really matters is how much kernel memory you are allotted when they set up the VPS and I assume that is dependent on how many VPS's are on the server.

So, my new VPS gives me slightly less memory than my old - which is causing hpptd to crash - even with this light weekend traffic. I am going to hate to see what happens after this long weekend!

Any ideas as to what I can change to reduce this memory usage - which incidentally seems to be high even when the forums are closed?

Something doesn't seem right as it seems from the memory being used that I need a dedicated server and not a VPS just to run the BB.
Posted By: JAISP

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/25/08 08:01 PM

Are you getting CPU exceeded pages and such on your site?

I have seen this with many hosting companies causing many interactive sites to be CPU limited and causing outages on the site.
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/25/08 08:08 PM

I am not really sure what you are asking as I really do not know much about the technical end smile

Right now though, with about half the normal traffic I receive "server load" is flashing red at "2.19" so another crash is imminent by the looks of things.
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/25/08 09:34 PM

I might have jumped to some false conclusions about the memory limits and was reading some numbers wrong. The culprit may be statistics software running in the background. I have limited when they can run now so I will have to monitor this I guess.
Posted By: Gizmo

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 02:11 AM

You may need to tune apache to work properly on the new server; it's usually configured (by default) to have ultimately unlimited resources
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 03:01 AM

You have'nt written one of your excellent FAQs on the subject by any chance have you?

I was searching the net for one and keep finding links to one that sounds excellent - but the site no longer exists...
Posted By: Gizmo

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 03:12 AM

Well, it can honestly vary, and a lot of it can be just trial and error... We have 384mb ram allocated, so our config is tuned low:
Code
<IfModule prefork.c>
StartServers            8
MinSpareServers         5
MaxSpareServers         20
ServerLimit             30
MaxClients              30
MaxRequestsPerChild     8000
</IfModule>
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 03:25 AM

Thanks Gizmo, that gives me a starting point.

I am using WHM and they have a link there for Memory Restrictions - "This tool will calculate new Apache memory limits based upon past memory usage. The new memory limits will be updated in the Apache configuration."

I don't know if using this would be a good thing or a bad thing - does anyone have any experience with this tool? If I am crashing because of lack of memory it seems to me using a "Memory Restriction" tool may not be what I am looking for...
Posted By: Gizmo

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 03:41 AM

Personally, I find these CP's everyone uses for small setups overkill... they use a lot of resources lol.. you probably run under 20 sites on your vps? I run over 50, and just use WebMin/VirtualMin, which leave a tiny footprint on the server.

Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 03:52 AM

Gizmo, you have MaxRequestsPerChild 8000
I have MaxRequestsPerChild 0 - zero, diddly - can't be good, can it?
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 04:07 AM

I guess O actually means "unlimited" so not a problem perhaps.
Posted By: Gizmo

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 06:00 AM

I was about to post this:
Quote:
The MaxRequestsPerChild directive sets the limit on the number of requests that an individual child server process will handle. After MaxRequestsPerChild requests, the child process will die. If MaxRequestsPerChild is 0, then the process will never expire.


Till I saw your other reply lol...

Not sure how it'll work with 0, I think it'll just keep the apache proces alive all the time vs killing it; so if you spawn too many child processes they'll all remain, which could actually be bad...
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 12:21 PM

Quote:
you probably run under 20 sites on your vps?


Just the one site on this server- the forum. I chose cpanel because I am more familiar with it than I am with others - and it helps with my command-line-avoidance smile

About the MaxRequestsPerChild - from what I was reading last night, putting a limit on the setting only is needed on a few certain servers - Solaris being mentioned if I recall correctly.

Last night I relaized that I could also check the "use persistent connections" box in the forum control panel - which would control the numbers of childs to some degree (if I understand the concept correctly) and aso reduce CPU usage to some degree I believe.
Posted By: Gizmo

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 12:56 PM

Lol, please do yourself a favor, do not ever click that option (persistent connections) unless you own the server and have several gigs of ram available...
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 01:05 PM

Sounds like you are speaking from experience on that - unchecking the box as I type....
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/26/08 08:22 PM

So today it was mysql that crashed - not apache. A pattern has developed - the server's bandwidth statistics script runs every 6 hours and drives my server load up from the .5 to .9 range to the 2.4 or higher "red" range - which this afternoon resulted in the database crash.

I can't seem to find a way to change when the bandwidth stats are run - or to turn them off. I have contacted support - they must be getting tired of me by now smile
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/27/08 12:41 AM

Quote:
I just moved to a new VPS which on paper is better than my old VPS - faster processor, more RAM, more bandwidth, etc. - but I have just discovered it all means nothing.

Apparently the only thing that really matters is how much kernel memory you are allotted when they set up the VPS


I guess this statement really was correct. I have been having problems because I keep reaching my kmemsize limit - which, it turns out is only a fraction of what I had on the old server - even though the new server's advertised specs are much better. No one advertises "kmemsize".

Perhaps the support people don't even know what it is as they keep saying kmemsize is a result of not enough ram and I need more ram (already have 50% more than on the old server).

A quick search on Google says that kmemsize is "the size of unswappable kernel memory allocated for the internal kernel structures for the processes of a particular VPS."

That does not sound like ram to me.

So, before signing up for any hosting I suggest asking about kmemsize.
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/27/08 01:52 PM

Overnight I moved back to my old server (with more kmemsize) and this morning support at the new server finally got around to answering my question - confirming that all of their plans have the same kmemsize - so if you buy the top of the line plan your forum will run no better than if you opt for the cheapest - as the weak link in the chain is kmemsize - and that information is not available on hosting companies websites....
Posted By: SD

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/27/08 03:07 PM

you could move to my dedicated server box and not worry about kmemsize laugh
Posted By: doug

Re: Apache Crashing Due to Memory Limit Being Reached On VPS - 05/27/08 03:33 PM

I am going to have to do something as moving back to my old host is just temporary. I am going to let things settle for a couple of weeks (hopefully) and let members forget about the recent disruptions before actually moving again.

I do want to move though as I have no confidence in my current host and I would like to have an uneventful summer spent fishing, golfing, and traveling - not worrying about whether the forums are up and running.

Perhaps you could PM me some info Sirdude?
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