@ Charles-François Natali <report@bugs.python.org> wrote (2011-05-13 13:24+0200):
> I happily posted a reinit patch

I must say in advance that we have implemented our own thread
support 2003-2005 and i'm thus lucky not to need to use anything
else ever since.  So.  And of course i have no overview about
Python.  But i looked and saw no errors in the default path and
the tests run without errors.
Then i started to try your semaphore path which is a bit
problematic because Mac OS X doesn't offer anon sems ;).
(
By the way, in PyThread_acquire_lock_timed() these lines

    if (microseconds > 0)
                MICROSECONDS_TO_TIMESPEC(microseconds, ts);

result in these compiler warnings.

python/thread_pthread.h: In function ‘PyThread_acquire_lock_timed’:
Python/thread_pthread.h:424: warning: ‘ts.tv_sec’ may be used
uninitialized in this function
Python/thread_pthread.h:424: warning: ‘ts.tv_nsec’ may be used
uninitialized in this function
)

#ifdef USE_SEMAPHORES
#define broken_sem_init broken_sem_init
static int broken_sem_init(sem_t **sem, int shared, unsigned int value) {
    int ret;
    auto char buffer[32];
    static long counter = 3000;
    sprintf(buffer, "%016ld", ++counter);
    *sem = sem_open(buffer, O_CREAT, (mode_t)0600, (unsigned int)value);
    ret = (*sem == SEM_FAILED) ? -1 : 0;
    //printf("BROKEN_SEM_INIT WILL RETURN %d (value=%u)\n", ret,value);
    return ret;
}
static int sem_timedwait(sem_t *sem, struct timespec *ts) {
    int success = -1, iters = 1000;
    struct timespec now, wait;
    printf("STARTING LOOP\n");
    for (;;) {
        if (sem_trywait(sem) == 0) {
            printf("TRYWAIT OK\n");
            success = 0;
            break;
        }
        wait.tv_sec = 0, wait.tv_nsec = 200 * 1000;
        //printf("DOWN "); fflush(stdout);
        nanosleep(&wait, NULL);
        MICROSECONDS_TO_TIMESPEC(0, now);
        //printf("WOKE UP NOW=%ld:%ld END=%ld:%ld\n", now.tv_sec,now.tv_nsec, ts->tv_sec,ts->tv_nsec);
        if (now.tv_sec > ts->tv_sec ||
            (now.tv_sec == ts->tv_sec && now.tv_nsec >= ts->tv_nsec))
            break;
        if (--iters < 0) {
            printf("BREAKING OFF LOOP, 1000 iterations\n");
            errno = ETIMEDOUT;
            break;
        }
    }
    return success;
}
#define sem_destroy sem_close

typedef struct _pthread_lock {
    sem_t               *sem;
    struct _pthread_lock*next;
    sem_t               sem_buf;
} pthread_lock;
#endif

plus all the changes the struct change implies, say.
Yes it's silly, but i wanted to test.  And this is the result:

== CPython 3.3a0 (default:804abc2c60de+, May 14 2011, 01:09:53) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)]
==   Darwin-10.7.0-i386-64bit little-endian
==   /Users/steffen/src/cpython/build/test_python_19230
Testing with flags: sys.flags(debug=0, inspect=0, interactive=0, optimize=0, dont_write_bytecode=0, no_user_site=0, no_site=0, ignore_environment=1, verbose=0, bytes_warning=0, quiet=0)
Using random seed 1362049
[1/1] test_threading
STARTING LOOP
test_acquire_contended (test.test_threading.LockTests) ... ok
test_acquire_destroy (test.test_threading.LockTests) ... ok
test_acquire_release (test.test_threading.LockTests) ... ok
test_constructor (test.test_threading.LockTests) ... ok
test_different_thread (test.test_threading.LockTests) ... ok
test_reacquire (test.test_threading.LockTests) ... ok
test_state_after_timeout (test.test_threading.LockTests) ... ok
test_thread_leak (test.test_threading.LockTests) ... ok
test_timeout (test.test_threading.LockTests) ... STARTING LOOP
TRYWAIT OK
FAIL
test_try_acquire (test.test_threading.LockTests) ... ok
test_try_acquire_contended (test.test_threading.LockTests) ... ok
test_with (test.test_threading.LockTests) ... ok
test__is_owned (test.test_threading.PyRLockTests) ... ok
test_acquire_contended (test.test_threading.PyRLockTests) ... ok
test_acquire_destroy (test.test_threading.PyRLockTests) ... ok
test_acquire_release (test.test_threading.PyRLockTests) ... ok
test_constructor (test.test_threading.PyRLockTests) ... ok
test_different_thread (test.test_threading.PyRLockTests) ... ok
test_reacquire (test.test_threading.PyRLockTests) ... ok
test_release_unacquired (test.test_threading.PyRLockTests) ... ok
test_thread_leak (test.test_threading.PyRLockTests) ... ok
test_timeout (test.test_threading.PyRLockTests) ... STARTING LOOP
TRYWAIT OK
FAIL
test_try_acquire (test.test_threading.PyRLockTests) ... ok
test_try_acquire_contended (test.test_threading.PyRLockTests) ... ok
test_with (test.test_threading.PyRLockTests) ... ok
test__is_owned (test.test_threading.CRLockTests) ... ok
test_acquire_contended (test.test_threading.CRLockTests) ... ok
test_acquire_destroy (test.test_threading.CRLockTests) ... ok
test_acquire_release (test.test_threading.CRLockTests) ... ok
test_constructor (test.test_threading.CRLockTests) ... ok
test_different_thread (test.test_threading.CRLockTests) ... ok
test_reacquire (test.test_threading.CRLockTests) ... ok
test_release_unacquired (test.test_threading.CRLockTests) ... ok
test_thread_leak (test.test_threading.CRLockTests) ... BREAKING OFF LOOP, 1000 iterations
Timeout (1:00:00)!
Thread 0x00007fff70677ca0:
  File "/Users/steffen/src/cpython/Lib/test/lock_tests.py", line 17 in _wait
  File "/Users/steffen/src/cpython/Lib/test/lock_tests.py", line 52 in wait_for_finished
  File "/Users/steffen/src/cpython/Lib/test/lock_tests.py", line 152 in test_thread_leak
  File "/Users/steffen/src/cpython/Lib/unittest/case.py", line 407 in _executeTestPart
  File "/Users/steffen/src/cpython/Lib/unittest/case.py", line 462 in run
  File "/Users/steffen/src/cpython/Lib/unittest/case.py", line 514 in __call__
  File "/Users/steffen/src/cpython/Lib/unittest/suite.py", line 105 in run
  File "/Users/steffen/src/cpython/Lib/unittest/suite.py", line 67 in __call__
  File "/Users/steffen/src/cpython/Lib/unittest/suite.py", line 105 in run
  File "/Users/steffen/src/cpython/Lib/unittest/suite.py", line 67 in __call__
  File "/Users/steffen/src/cpython/Lib/unittest/runner.py", line 168 in run
  File "/Users/steffen/src/cpython/Lib/test/support.py", line 1187 in _run_suite
  File "/Users/steffen/src/cpython/Lib/test/support.py", line 1213 in run_unittest
  File "/Users/steffen/src/cpython/Lib/test/test_threading.py", line 748 in test_main
  File "/Users/steffen/src/cpython/Lib/test/regrtest.py", line 1044 in runtest_inner
  File "/Users/steffen/src/cpython/Lib/test/regrtest.py", line 838 in runtest
  File "/Users/steffen/src/cpython/Lib/test/regrtest.py", line 662 in main
  File "/Users/steffen/src/cpython/Lib/test/__main__.py", line 13 in <module>
  File "/Users/steffen/src/cpython/Lib/runpy.py", line 73 in _run_code
  File "/Users/steffen/src/cpython/Lib/runpy.py", line 160 in _run_module_as_main

Hope that helps a bit. Bâillement.