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Topic: PHP Caching extensions accessing shared memory

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Topic: PHP Caching extensions accessing shared memory

[C0nw0nk]

So i noticed something strange going on with wincache on my servers. When lets say a php process hits its max number of served requests.

[ng4win]

None of them really use shared memory as they should on windows, trying to convince the developers has been a waste of (my) time..... so yes each process has its own cache and of-course is dropped on reload.
Looking at cache stats is mostly meaningless as you have no grip on which cache your looking at.

[C0nw0nk]

Just as i thought a pitty realy but hopefully some point in the future they get their heads around it.

I think memcached if you install and run that on a port on your server and use the php_memcached.dll that is a soloution but the last time i tried with memcache i remember it kept crashing not the most friendly or stable thing on windows.

I wounder if Jan-E would know of a soloution to this since he has fixed so many PHP extensions and ported them to windows too.

[ng4win]

Its quite simple but needs a proper programmer...

http://msdn.microsoft.com/en-us/library/windows/desktop/ms686958%28v=vs.85%29.aspx
http://www.boost.org/doc/libs/1_41_0/doc/html/interprocess/sharedmemorybetweenprocesses.html

[C0nw0nk]

Hmmm i wounder if its worth finding a freelancer for this.

https://www.elance.com/

I take it XCache is more suited for the job than Wincache.

[ng4win]

I don't think it makes a difference, the whole job is making a shared memory module with an api and changing ??cache to use the api instead. Memcache would be good to start with.

[C0nw0nk]

Well i used memcached on windows a long time ago and i had to stop using it because it kept crashing. Idk if its been updated or fixed and i dont even know where you would get the binaries from now.

[ng4win]

I didn't mean to use memcache but to use the source as a base.

This module should;
- allocate x amount of memory and lock it
- wait for a semaphore (API)

??cache should;
- Change its memory management to use API

Inter IO is much faster then a tcp port, its the same way nginx uses the pid file (sort of an API) in order to know who to talk to about shared resources.

But then again, if xcache or whatever-cache was rewritten in Lua we could cache anything(php,py,perl,etc.) and have its cache shared automatically.

[C0nw0nk]

Sounds like it will be a big and exspensive task aslo i am currently just toying with xcache and a joomla 3.x install.

[ng4win]

In the next release I've added some xcache stuff;

php-xcache-example.ini

[puertoblack2003]

can xcache run together with memcache?

[Jan-E]

[ng4win]

Maybe, haven't tested it yet, but the big question is, when you load multiple php-cgi instances are those instances going to use 1 shared memory pool or not?

The basic xcache design is 1 master which spawns children who use the master shared memory pool, in Windows this doesn't work so you have to run X masters and loadbalance the workload between them (running on different ports) each using its own memory pool.

When using opcache the load(balance) mechanism is not going to change, so if opcache uses a shared pool between all instances who is going to 'master' the pool?

[Jan-E]

Yes, more instances of php-cgi share the same memory pool. As far as I know no one masters the pool. There is no need for that when you see the pool as a collection of precompiled PHP-files with an index.

Just try it and see what happens with https://github.com/rlerdorf/opcache-status

The caveat: you cannot use OPcache on Windows for different PHP-versions. I tried to achieve this by compling a php_opcache64.dll with another fixed address, but it never became stable enough for production. So at the moment I am using PHP 5.3 as mod_php with XCache (Drupal 6) alongside PHP 5.6.5 NTS as mod_fcgid with OPcache.

See also https://github.com/zendtech/ZendOptimizerPlus/issues/109#issuecomment-20572357

[C0nw0nk]

So isit worth downloading the latest (Also i only use the 64bit binaries.) http://windows.php.net/download/

5.6.x branch enabling
extension=php_opcache.dll

And to use that instead of wincache i suppose the reason they ship opcache inside the zip archive is because it must be using shared memory.

I also have to toy about and figure out the best settings for production with opcache in a high traffic enviorment.


Also reading the documentation am i suppose to set a mmap base name ?

http://php.net/manual/en/opcache.configuration.php#ini.opcache.mmap-base

[ng4win]

Well I switched over and so far so good.

[Jan-E]

Yes, it is worth downloading. Installation is with

zend_extension=php_opcache.dll

The dll is in the zip-file for every release because it is a core extension of PHP. It is the preferred opcaching extension by the PHP developers. Probably it will be enables by default in PHP7.

Just use the default parameters to start with. They are in the readme of https://github.com/zendtech/ZendOptimizerPlus

[ng4win]

Is there any way to find out the base address all instances are using to verify they all use the same space?

[Jan-E]

C:\>type c:\Windows\ZendOPcache.MemoryBase@SYSTEM
20000000

The mmap_base is stored in a semaphore file called ZendOPcache.MemoryBase*. The '20000000' in my semaphore file is the fixed value that is compiled into the x86 opcache.dll:
https://github.com/zendtech/ZendOptimizerPlus/blob/master/shared_alloc_win32.c#L188

With x64 Windows I have seen different values in the semaphore file after each reboot:
https://github.com/zendtech/ZendOptimizerPlus/issues/109#issuecomment-22377260

BTW: did you try opcache.php from Rasmus Lerdorf?
https://github.com/rlerdorf/opcache-status

Rasmus Lerdorf launched PHP 1.0 back in 1995:
https://groups.google.com/forum/#!topic/comp.infosystems.www.authoring.cgi/PyJ25gZ6z7A/overview

[ng4win]