CODEWITHSUNDEEP
c++multithreading
shura-astrozero
shura-astrozero

Reputation: 175

GNU pth vs. pthread

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?

Upvotes: 4

Views: 5115

Answers (3)

白川 マセル
白川 マセル

Reputation: 39

I think GNUs PTH is meaned for C in the first place. You can use it on C++ too but C++ have its own anyway.

There are quite some applications using pth like low-level burning tools (and so GUI-Tools like K3B and Brasero depend on pth), also GnuPG uses PTH, the package management of Archlinux and some multimedia stuff.

On Windows its always a bit complicated. Microsoft did never get over the fact that C is the Programming Language from/for UNIX-Systems and so is suffering the NIH Symptome (Not Invented Here)

So they do a lot of stuff without any advantage just to be different.

If you use an Application which should run everywhere and its not low-level, use Qt with its QThreads and QThreadPool

  1. Its 100% the same on all operating systems
  2. You need much less code

If you write an "low-level" application i recommend to split your applications into backends and frontends and write a own backend for each OS and use the library which will do the least problems.

Upvotes: 1

antlersoft
antlersoft

Reputation: 14751

Gnu PTH is for a very limited use case: you want to use a multi-threaded implementation paradigm but you don't want to use multiple CPUs or cores and you don't want to rely on any OS or kernel-level support. Since almost all general-purpose CPUs now have multiple cores, this use case is increasingly irrelevant.

Windows has a separate threading model from POSIX; if you want your application to be cross-platform it is best to use a cross-platform threading library such as boost::thread.

Upvotes: 3

Jonathan Wakely
Jonathan Wakely

Reputation: 171403

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.)

Upvotes: 5

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