The problem is that I don't know how to check in test_threadsignals which thread implementation is used in Python. It would be nice to have some functions providing such information in the sys or sysconfig module, maybe something like sys.float_info.

For example, sys._thread_info can be a dict like {'name': 'pthread', 'use_semaphore': True}.

Keys:
 - name: cthread, lwp, nt, os2, pth, pthread, sgi, solaris or wince (sgi, lwp, pth, cthread may be removed from Python 3.3: #11876)
 - maxproc: max # of threads that can be started (SGI only)
 - stacksize: default stacksize for a thread (lwp, pthread and os2 only)
 - min_stacksize: minimum stacksize for a thread (pthread, nt and os2 only)
 - max_stacksize: maximum stacksize for a thread (nt and os2 only)

thread_pthread.h contains many #ifdef which may be interesting to have in thread_info:
 - if _HAVE_BSDI is defined, don't use pthread_init()
 - if THREAD_STACK_SIZE is defined, set the size of the thread stack
 - if PTHREAD_SYSTEM_SCHED_SUPPORTED is defined: set scope to PTHREAD_SCOPE_SYSTEM
 - if (defined(_POSIX_SEMAPHORES) && defined(HAVE_BROKEN_POSIX_SEMAPHORES) && defined(HAVE_SEM_TIMEDWAIT)): use semaphore

Well, the most important informations for this issue is the name of the thread implementation (pthread) and know if pthread semaphore are used or not.