ost Unix variants,
from GNU/Linux to MacOS X) and Win32 threads.  OpenMP threads, which
are supported in many common compilers (e.g. gcc) are also supported,
and may give better performance on some systems.  (OpenMP threads are
also useful if you are employing OpenMP in your own code, in order to
minimize conflicts between threading models.)  If you have a
shared-memory machine that uses a different threads API, it should be
a simple matter of programming to include support for it; see the file
<code>thread