On Sat, Sep 11, 2010 at 8:50 PM, Shawn McKenzie nos...@mckenzies.net wrote:
On 09/10/2010 11:13 AM, J Ravi Menon wrote:
Hi,
I have some basic questions on running php (5.2.x series on Linux
2.6) as a standalone daemon using posix methods (fork() etc..):
#!/usr/bin/php
?php
require_once ('someclass.php');
// do some initializations
.
// main 'forever' loop - the '$shutdown' will
// be set to true via a signal handler
while(!$shutdown)
{
$a = new SomeClass();
$a-doSomething()
}
// shutdown logic.
The 'someclass.php' in turn will include other files (via require_once).
The above file will be executed directly from the shell. The main loop
could be listening to new requests via sockets etc..
Few questions:
1) Does opcode cache really matter in such cli-based daemons? As
'SomeClass' is instantiated at every loop, I am assuming it is only
compiled once as it has already been 'seen'.
I am not very clear on how apc (or eaccelerator) works in such cases.
2) What about garbage collection? In a standard apache-mod-php setup,
we rely on the end of a request-cycle to free up resources - close
file descriptiors, free up memory etc..
I am assuming in the aforesaid standalone daemon case, we would
have to do this manually? In the loop above, would it be better to
'unset($a)' explicitly at the end of it before
it goes to the next iteration?
Note: I have written pre-forker deamons in php directly and
successfully deployed them in the past, but never looked at in depth
to understand all the nuances. Anecdotally, I have
done 'unset()' at some critical places were large arrays were used,
and I think it helped. AFAIK, unlike Java, there is no 'garbage
collector' thread that does all the magic?
Thanks,
Ravi
If I have time when you reply I'll answer the questions, but I must ask:
Is this purely academic? Why is this a concern? Have you encountered
issues? If so, what?
@Tom: I have compiled php with pcntl on and this has never been an
issue. It works well (on a linux setup), and I have deployed
standalone daemons with out any major problems. I have a home-grown
'preforker' framework (which I hope to share soon) which can be used
to exploit multi-core boxes.
@Shawn: It is not academic. There is a follow-up I am planning based
on the doubts above. I have deployed such daemons in the past with
some assumptions on (2) by doing manual cleanups - e.g. closing curl
connections, closing up db handles etc... Really want to understand
how php works in such setups outside of apache+mod_php.
thanks,
Ravi
--
Thanks!
-Shawn
http://www.spidean.com
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