GNU pth vs. pthread

Question

I want to build a portable and efficient server in C++; it will have lots of clients trying to connect at the same time, so it must be able of handling each request parallel.

I have been trying to find documentation, guides... etc. for multithreading. I have found a lot about POSIX Pthread, but almost nothing for GNU Pth (apart from the official manual in gnu.org).

So, can anyone explain me the difference between POSIX Pthread and GNU Pth? Please, I want the response not to be a copy of Wikipedia's contents (keep in mind that I'm an absolute newbie to multithreading). I want my server to be portable and efficient between all *nix-based systems, keeping away of using heavy fork()s.

Thanks for your help.

PS: I think it's better to ask this here: what about Windows? Are Pthreads or Pth an option there? If not, what is the API for that operating system?

Answer 1

Use Pthreads, it's much more widely used, so there is far more information and support available for it. I've never met anyone who actually uses GNU Pth. Or better yet if you are using C++11 use std::thread and if not then use boost::thread.

So, can anyone explain me the difference between POSIX Pthread and GNU Pth?

Pthreads is a cross-platform standard for pre-emptible multithreading, meaning (usually) the OS kernel manages the threads and the OS scheduler decides when each thread gets to run (if you have a single core only one thread can run at a time, if you have multiple cores multiple threads can run at a time). The OS scheduler could pause any thread at (almost) any time and let another thread run, so each thread gets a limited "time slice" and then other threads get to run.

GNU Pth is a non-preemptible user-space threading library, meaning the threads and which ones run at which time are decided in user-space not by the kernel. Some people say programs using non-preemptible threading libraries are easier to understand, because your thread won't get paused at arbitrary times for another thread to run.

I want my server to be portable and efficient between all *nix-based systems, keeping away of using heavy fork()s.

fork is not heavy on UNIX.

what about W*ndows? Are Pthreads or Pth an option there? If not, what is the API for that operating system?

There are pthreads APIs for Windows, but they're not native to the Windows OS. I don't know if GNU Pth works on Windows - I doubt it, unless you use Cygwin. Windows has its own Win32 thread model.

Using std::thread or boost::thread is portable to POSIX platforms and Windows, and makes certain parts of the API easier to use (specifically, locking and unlocking mutexes can be easily done in an exception safe way and condition variables are easier to use.)