Working with Threads using Apache and PHP

Question

Is there anyway to work with threads in PHP via Apache (using a browser) on Linux/Windows?

Answer 1

The idea of "thread safe" can be very broad. However PHP is on the very, furthest end of the spectrum. Yes, PHP is threadsafe, but the driving motivation and design goals focus on keeping the PHP VM safe to operate in threaded server environments, not providing thread safe features to PHP userspace. A huge amount of sites use PHP, one request at a time. Many of these sites change very slowly - for example statistics say more sites serve pages without Javascript still than sites that use Node.js on the server. A lot of us geeks like the idea of threads in PHP, but the consumers don't really care. Even with multiple packages that have proved it's entirely possible, it will likely be a long time before anything but very experimental threads exist in PHP.

Each of these examples (pthreads, pht, and now parallel) worked awesome and actually did what they were designed to do - as long as you use very vanilla PHP. Once you start using more dynamic features, and practically any other extensions, you find that PHP has a long way to go.

Answer 2

The mere fact that it is possible to do something, says nothing whatever about whether it is appropriate.

The facts are, that the threading model used by pthreads+PHP is 1:1, that is to say one user thread to one kernel thread.

To deploy this model at the frontend of a web application inside of apache doesn't really make sense; if a front end controller instructs the hardware to create even a small number of threads, for example 8, and 100 clients request the controller at the same time, you will be asking your hardware to execute 800 threads.

pthreads can be deployed inside of apache, but it shouldn't be. What you should do is attempt to isolate those parts of your application that require what threading provides and communicate with the isolated multi-threading subsystem via some sane form of RPC.

I wrote pthreads, please listen.

Answer 3

Highly discouraged.

The pcntl_fork function, if allowed at all in your setup, will fork the Apache worker itself, rather than the script, and most likely you won't be able to claim the child process after it's finished. This leads to many zombie Apache processes.

I recommend using a background worker pool, properly running as a daemon/service or at least properly detached from a launching console (using screen for example), and your synchronous PHP/Apache script would push job requests to this pool, using a socket.

Does it help?

[Edit] I would have offered the above as a commment, but I did not have enough reputation to do so (I find it weird btw, to not be able to comment because you're too junior).

[Edit2] pthread seems a valid solution! (which I have not tried so I can't advise)