diff options
Diffstat (limited to 'Lib/multiprocessing')
| -rw-r--r-- | Lib/multiprocessing/semaphore_tracker.py | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/Lib/multiprocessing/semaphore_tracker.py b/Lib/multiprocessing/semaphore_tracker.py index 3e31bf8..82833bc 100644 --- a/Lib/multiprocessing/semaphore_tracker.py +++ b/Lib/multiprocessing/semaphore_tracker.py @@ -23,6 +23,9 @@ from . import util __all__ = ['ensure_running', 'register', 'unregister'] +_HAVE_SIGMASK = hasattr(signal, 'pthread_sigmask') +_IGNORED_SIGNALS = (signal.SIGINT, signal.SIGTERM) + class SemaphoreTracker(object): @@ -43,10 +46,16 @@ class SemaphoreTracker(object): with self._lock: if self._pid is not None: # semaphore tracker was launched before, is it still running? - pid, status = os.waitpid(self._pid, os.WNOHANG) - if not pid: - # => still alive - return + try: + pid, _ = os.waitpid(self._pid, os.WNOHANG) + except ChildProcessError: + # The process terminated + pass + else: + if not pid: + # => still alive + return + # => dead, launch it again os.close(self._fd) self._fd = None @@ -68,7 +77,19 @@ class SemaphoreTracker(object): exe = spawn.get_executable() args = [exe] + util._args_from_interpreter_flags() args += ['-c', cmd % r] - pid = util.spawnv_passfds(exe, args, fds_to_pass) + # bpo-33613: Register a signal mask that will block the signals. + # This signal mask will be inherited by the child that is going + # to be spawned and will protect the child from a race condition + # that can make the child die before it registers signal handlers + # for SIGINT and SIGTERM. The mask is unregistered after spawning + # the child. + try: + if _HAVE_SIGMASK: + signal.pthread_sigmask(signal.SIG_BLOCK, _IGNORED_SIGNALS) + pid = util.spawnv_passfds(exe, args, fds_to_pass) + finally: + if _HAVE_SIGMASK: + signal.pthread_sigmask(signal.SIG_UNBLOCK, _IGNORED_SIGNALS) except: os.close(w) raise @@ -104,12 +125,13 @@ register = _semaphore_tracker.register unregister = _semaphore_tracker.unregister getfd = _semaphore_tracker.getfd - def main(fd): '''Run semaphore tracker.''' # protect the process from ^C and "killall python" etc signal.signal(signal.SIGINT, signal.SIG_IGN) signal.signal(signal.SIGTERM, signal.SIG_IGN) + if _HAVE_SIGMASK: + signal.pthread_sigmask(signal.SIG_UNBLOCK, _IGNORED_SIGNALS) for f in (sys.stdin, sys.stdout): try: |