Kent Larsson wrote:
Thank you for your answer. I was hoping there were a solution. :-/ It would
have been nice as PHP has a large install base and is a quite common element
in cheap web hosting solutions. Has anyone else got any more comments or
suggestions?
In absence of shared memory and threads. What I really must have is some
kind of mutex functionality. I will be manipulating files on disk and I
don't want two instances to be able to touch the disk at the same time. Is
there something I could use for mutual exclusion? If there aren't any
dedicated methods, are there 100% reliable workarounds?
If you are looking for shared memory such that one request can then
access an object created once (e.g. "primed") and stored for subsequent
reuse, then this is totally possible.
Using something like memcached or APC you can access such shared memory
etc. Access to APC shared memory is protected using various locking
methods, including File Locks (mmap), IPC Semaphores, Spinlocks and
PThread Mutexs.
While you cannot run threads in a Web based environment very easily, you
can fork child processes: http://uk.php.net/pcntl_fork. I'm not sure I'd
recommend this for a web environment tho! Depending what you are doing
tho' you may want to run a small "daemon" that listens for connections
and spawns off a new process to deal with it via this method. It really
depends what you are trying to achieve as all of the timing/locking
problems of asynchronous programming are typically something I would try
and avoid in a web/scripting environment.
HTHs
Col
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http://colin.guthr.ie/
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