The installation of pthreads in PHP (for the use of Threaded, Thread, Worker, Pool, etc) is quite "complex" and that's not very pratical when you use packages of your Linux ditribution that doesn't have ZTS enabled (you have to download PHP sources and compile them — auxiliary question : why ZTS isn't activated by default?).
Few days ago I tested HHVM for the first time and the performance is just... impressive. I'm writing a kind of server in PHP and I need threads. I thought that HHVM support them natively. That's not the case (unknown class).
I can find documentation on pthreads on HHVM documentation, but that's the official PHP docs. I read somewhere on the Internet that HHVM doesn't support Threads.
So... if threads are supported in HHVM, how to install pthreads on HHVM? What about ZTS?
ZTS is a prerequisite of pthreads.
ZTS is not used as the default because ZTS mode has some overhead associated with it.
The HHVM documentation is just a clone of the php-doc repository, restyled, with some additional sections added for HHVM, this is why the pthreads documentation shows up in HHVM docs.
HHVM does not and will not support pthreads, or at least, I won't be supporting it, and I wrote pthreads.
HHVM does support concurrency through asynchronous programming, arguably this fits the use case of writing a server better than parallelism: http://docs.hhvm.com/manual/en/hack.async.php
I have no idea how good that is, the documentation calls it "basic support".