Re: APC & __autoload & webclusters

Nathan Nobbe schreef:

On Thu, Feb 21, 2008 at 12:01 PM, Jochem Maas <jochem@iamjochem.com> wrote:

Richard Lynch schreef:

If it's that inter-tangled, then I would hazard a WILD GUESS that the __autoload will still end up loading everything...

but not on every request ;-) ... I do use output caching, and I know not everything is actually used in every request.

i think youre good to go w/ autoload not loading everything up, but what about existing include / require directives? if the code doesnt already use __autoload() its almost certainly strewn w/ these. so i think if you want the boost from __autoload, not loading up everything, youll at least have to strip these out.

I know, I have ... I wrote the code in the first :-)

I know - but it's a rubbish solution because it offer no control as to what

is cleared from the APC cache, sometimes I want to clear opcodes, sometimes user-data, sometimes both ... graceful means being forced to clear everything.

you can pass a parameter to apc_clear_cache() http://www.php.net/manual/en/function.apc-clear-cache.php that distinguishes what you want to clear; user data or cached opcode. obviously calling it from the cli will not clear the webserver user cache though.

I know apc_clear_cache() ... the whole problem is doing it on multiple servers. your statement about not being able to do it from the CLI (which I know) is half correct AFAICT - you can't clear anything cached in APC via mod_php from the CLI ... which is my whole problem in a nutshell :-)

One would think that there was something like this indeed - I cannot find

it, but then there must be something ... I assume, for instance, that Yahoo!** occassionally see fit to clear APC caches on more than one machine and I doubt Rasmus sits there and opens a browser to run apc.php on each one ;-)

i dont know how yahoo does it, but i do know a little about how facebook does it; they had 3 speakers at the dc php conference last year. i think you might find these slides helpful, (sorry for the ridiculuus url) http://www.google.com/url?sa=t&ct=res&cd=1&url=http%3A%2F%2Ftekrat.com%2Ftalks_files%2Fphpdc2007%2Fapc%40facebook.pdf&ei=tce9R9T4FqrszATeiZG6CA&usg=AFQjCNF_1Ecm2cL1EINgRQG9k3fTEclzpA&sig2=ifrJK545M2liBdXbRrHrIw

thanks for that link - it gives me a few angles and ideas to work on!

you can use capistrano to deploy the new files; but it may be more convenient to use php and http requests to update all the server caches; *just a thought*.

I'm not using capistrano for file deployment (files are stored centrally on a GFS volume to which all servers have access) ... I am (will be) using capistrano in order to run commands symultaneously on all webservers ... one of which will have to be some kind of cache control mechanism, which is the case of apc will probably be a php script that hits apc.php on the local machines webserver (but I want to be able to run said php script on multiple machines at once, or at least without having to log in to every machine ... and I see no reason to duplicate the functionality of capistrano, I just write a php script to do the actual apc.php interaction on the local webserver that cap can call on each machine.

there are optimizations that are possible as well, such as setting, apc.stat=0 and

got that one set already. :-)

using apc_compile_file() rather than clearing the entire cache, but these techniques add

I read the facebook story about preloading the cache (using memory dumping/loading) in combination with apc_compile_file() ... which is cool but a little too much effort given the time/budget I have to complete this (my client doesn't have X billion to burn ... but funnily enough they do have a viable business model ... but that's another story ;-)

complexity. it sounds like you just want to get a decent bumb w/o too much additional complexity, so i wouldnt recommend them here, but i thought id mention them in passing..

apart from writing some kind of management cli script to [remote] control the apc cache of each webserver I'm also going [to have to] incorporate memcache functionality into my current caching stuff - many thanks for that PDF link (I hadn't come accross it before in my searching, although I had discovered various other facebook+apc/memcache/caching related presentations) it's given me jsut enough code and ideas to hang myself with ... er I mean write a transparent memcache layer into my app :-)

-nathan