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Trivial C11 threads.h implementation over POSIX threads, and not-so-trivial implementation over Win32 threads.


Even though GCC provides the threading features required by the C11 standard (like atomics, and thread-local storage), GNU libc, still does not implement the necessary library functions of the standard C thread API. Other popular platforms similarly lack support for the C11 thread functions, like Microsoft's C runtime library on Windows.

If you're starting a new multithreaded project in C right now, it would make sense to use the standard C way of using threads instead of a mishmash of various platform-specific APIs. So until the system libc adds support for it, we need a stopgap that works exactly as the C standard describes.



I place this piece of code in the public domain. Feel free to use as you see fit. I'd appreciate it if you keep my name at the top of the code somewhere, but whatever.

How to use

With POSIX threads

On UNIX systems, or on Windows with a 3rd party pthreads library, c11threads is implemented as a thin wrapper of static inline functions over pthreads.

No installation or compilation necessary; just drop c11threads.h into your project source tree, and don't forget to link with -lpthread. On some platforms it might be required to also pass the -pthread flag to the compiler.

If your compiler does not support the inline keyword, define C11THREADS_INLINE to whatever equivalent keyword the compiler provides, or to the empty string to make all the functions simply static.

If you wish to use the pthreads implementation on Windows, in preference to the native win32 one, you need to define C11THREADS_PTHREAD_WIN32.

With Win32 threads

To use C11 threads over the Windows threads API, beyond adding c11threads.h to your project, you also need to compile c11threads_win32.c as part of your build. Additionally, if you're in a situation where letting c11threads keep resources for the duration of the process lifetime is not desirable, you can call c11threads_destroy_win32() to free them manually at any point, when you're done with it.

Test program

There's a simple test program under test/. To build it on UNIX (GNU/Linux, FreeBSD, MacOSX, whatever), simply change into the test directory and type make.

To build the test program on Windows with MSVC using native win32 threads, setup the build environment (usually there's a batch file called vcvars*.bat, run it in a console), and use microsoft nmake to build: nmake -f Makefile.msvc.


Main project site:

Feel free to send corrections, patches, trendy social pull requests, pictures of your cat wearing santa hats, any good porn links, or investment opportunities with Nigerian ex-royals... It's all good.