Method _do_wait

Lib/asyncio/unix_events.py:874–891

(self, pid, pidfd, callback, args)

        loop._add_reader(pidfd, self._do_wait, pid, pidfd, callback, args)

    def _do_wait(self, pid, pidfd, callback, args):
        loop = events.get_running_loop()
        loop._remove_reader(pidfd)
        try:
            _, status = os.waitpid(pid, 0)
        except ChildProcessError:
            # The child process is already reaped
            # (may happen if waitpid() is called elsewhere).
            returncode = 255
            logger.warning(
                "child process pid %d exit status already read: "
                " will report returncode 255",
                pid)
        else:
            returncode = waitstatus_to_exitcode(status)

        os.close(pidfd)
        callback(pid, returncode, *args)

class _ThreadedChildWatcher:
    """Threaded child watcher implementation.