_utils.py 文件源码

def _wait_forever(self):
        # Wait forever
        while True:
            # Check if signals have been received
            if os.name == "posix":
                self._empty_signal_pipe()
            self._run_signal_handlers()

            if os.name == "posix":
                # NOTE(sileht): we cannot use threading.Event().wait(),
                # threading.Thread().join(), or time.sleep() because signals
                # can be missed when received by non-main threads
                # (https://bugs.python.org/issue5315)
                # So we use select.select() alone, we will receive EINTR or
                # will read data from signal_r when signal is emitted and
                # cpython calls PyErr_CheckSignals() to run signals handlers
                # That looks perfect to ensure handlers are run and run in the
                # main thread
                try:
                    select.select([self.signal_pipe_r], [], [])
                except select.error as e:
                    if e.args[0] != errno.EINTR:
                        raise
            else:
                # NOTE(sileht): here we do only best effort
                # and wake the loop periodically, set_wakeup_fd
                # doesn't work on non posix platform so
                # 1 seconds have been picked with the advice of a dice.
                time.sleep(1)
                # NOTE(sileht): We emulate SIGCHLD, _service_manager
                # will just check often for dead child
                self._signals_received.append(SIGCHLD)