diff --git a/Lib/asyncio/unix_events.py b/Lib/asyncio/unix_events.py index 33a6732941f..e4f445e9502 100644 --- a/Lib/asyncio/unix_events.py +++ b/Lib/asyncio/unix_events.py @@ -1226,13 +1226,15 @@ class MultiLoopChildWatcher(AbstractChildWatcher): def close(self): self._callbacks.clear() - if self._saved_sighandler is not None: - handler = signal.getsignal(signal.SIGCHLD) - if handler != self._sig_chld: - logger.warning("SIGCHLD handler was changed by outside code") - else: - signal.signal(signal.SIGCHLD, self._saved_sighandler) - self._saved_sighandler = None + if self._saved_sighandler is None: + return + + handler = signal.getsignal(signal.SIGCHLD) + if handler != self._sig_chld: + logger.warning("SIGCHLD handler was changed by outside code") + else: + signal.signal(signal.SIGCHLD, self._saved_sighandler) + self._saved_sighandler = None def __enter__(self): return self @@ -1259,15 +1261,17 @@ class MultiLoopChildWatcher(AbstractChildWatcher): # The reason to do it here is that attach_loop() is called from # unix policy only for the main thread. # Main thread is required for subscription on SIGCHLD signal - if self._saved_sighandler is None: - self._saved_sighandler = signal.signal(signal.SIGCHLD, self._sig_chld) - if self._saved_sighandler is None: - logger.warning("Previous SIGCHLD handler was set by non-Python code, " - "restore to default handler on watcher close.") - self._saved_sighandler = signal.SIG_DFL + if self._saved_sighandler is not None: + return - # Set SA_RESTART to limit EINTR occurrences. - signal.siginterrupt(signal.SIGCHLD, False) + self._saved_sighandler = signal.signal(signal.SIGCHLD, self._sig_chld) + if self._saved_sighandler is None: + logger.warning("Previous SIGCHLD handler was set by non-Python code, " + "restore to default handler on watcher close.") + self._saved_sighandler = signal.SIG_DFL + + # Set SA_RESTART to limit EINTR occurrences. + signal.siginterrupt(signal.SIGCHLD, False) def _do_waitpid_all(self): for pid in list(self._callbacks):