Is there any cross-platform threading library in C++?

I'm looking for some easy to use cross-platform threading library written in C++.

What's your opinion on boost::thread or Pthreads? Does Pthreads run only on POSIX compliant systems?

What about the threading support 开发者_开发问答in the Qt library?

Boost.Thread is the draft for the coming standard threading library of the C++ language. Knowing that, I prefer to use it as it provide some strong guarantees (because it becomes standard).

Update: Now that we have the standard threading libraries, some more precisions. Some boost constructs, like boost::shared_mutex, have not been standardised (but might be later). However the standard library exploit the move semantic better. Good to know before choosing a library. Also, using C++11 threading library requires a compiler that provides it. It's not the case for all compilers today.

Update: Now [Nov2012] most of the Standard compilers provide C++11 threading library. VS2012, GCC4.8 and Clang3.1 have support for threads and synchronization primitives and atomic operations. For complete implementation you can also use just thread by Anthony Williams. It is C++11 compliant library supported on Windows/Mac and Linux.

Links for status of C++11 features with various compilers:

• GCC 4.8 - http://gcc.gnu.org/gcc-4.8/cxx0x_status.html
• Clang3.1 - http://clang.llvm.org/cxx_status.html
• VS2012 - http://msdn.microsoft.com/en-us/library/vstudio/hh567368.aspx

There is a threading library coming with C++11. It's built upon the boost threading library. Unfortunately, I seem to remember that there are non-trivial differences between Boost.Threads and what C++11 comes with. Still, if you plan to switch to the C++ standard threading library, I believe Boost.Threads is the closest you can get to now.

I suppose that, under the hood, these libraries will use Pthreads on POSIX systems and whatever native threading support is available elsewhere.

Disclaimer: I haven't worked with either of the two.

Pthreads are running only on POSIX systems. QThread from Qt is a way to go. It is available on platforms: Linux, Mac OS X, Windows, Embedded Linux, Windows CE, Symbian, Maemo.

Also have a look at OpenMP, it's a set of (somewhat standard) pragmas specifications that is supported by most major compilers. The good of OpenMP is that it's simple and that your code can be easily compiled in both single and multi-threaded versions.

Just a simple example:

std::vector<double> a, b;
...
double sum = 0.0;
...
#pragma omp parallel for reduction(+:sum)
  for (i=0; i < n; i++)
    sum = sum + (a[i] * b[i]);

It's obviously possible to do also more complex things.

I am surprised that nobody mentioned the Intel TBB library (linked to an another answer of mine). Also, a task-based implementation should be preferred over a thread-based.

Qt has pretty good thread support. If you just need to create a thread and run some code in it, QThread is all you need. There are many other high-level classes that can help you with thread pools or even abstract the concurrent execution (the QtConcurrent framework).

List the concerning platforms. If you're only using say, Linux/Mac/Windows, then boost::thread will likely do you fine until C++0x (harhar) provides std::thread.

I have used pthreads for code that work on multiple platforms. To get around the Windows lack of pthreads, I have used the following open source library with great success: POSIX Threads for Windows

wxWidgets has thread classes, and as wxWidgets is platform independent, it might just be the best thing for u.

Boost.Threads is built on top of PThreads on UNIX systems and Win32 Threads on Windows.

The boost library is syntactically simple and all of the hairy business of properly interfacing C++ code with C libraries is taken care of behind the scenes. If you're not very comfortable with C++, however, PThreads might seem more straight-forward with its simple C API.

Qt Threads is also a good library, but because I use several other boost libraries, I'll compile and link against Boost no matter what. I might not always link against Qt. And, well, I just don't want to remember how to use two different libraries.

SDL is simple, cross-platform and has threading support.

Pthread is part of Posix, but not every posix systems will have threads. pthreads is most portable.

What platforms will you support?