[New-bugs-announce] [issue32014] multiprocessing Server's shutdown method useless send message to manager

[stevezh]

New submission from stevezh <cisjiong at gmail.com>:

When shutdown the manager, Server's handle_request will send back message to the manager, so is useless for the Server's shutdown method send back "None" to the manager?

Source code from Lib/multiprocessing/managers.py:

    def shutdown(self, c):
        '''
        Shutdown this process
        '''
        try:
            util.debug('manager received shutdown message')
            # Is useless here?
            c.send(('#RETURN', None))
        except:
            import traceback
            traceback.print_exc()
        finally:
            self.stop_event.set()

Server's handle_request may throw and catch exception because the conn is closed in _finalize_manager() after Server's shutdown method returns.

code from handle_request():

        try:
            c.send(msg)
        except Exception as e:
            try:
                c.send(('#TRACEBACK', format_exc()))
            except Exception:
                pass

code from _finalize_manager():

            try:
                conn = _Client(address, authkey=authkey)
                try:
                    dispatch(conn, None, 'shutdown')
                finally:
                    conn.close()
            except Exception:
                pass

Also the Server's shutdown method only used by manager class.

----------
components: Library (Lib)
messages: 306142
nosy: davin, jnoller, pitrou, sbt, stevezh
priority: normal
severity: normal
status: open
title: multiprocessing Server's shutdown method useless send message to manager
type: behavior
versions: Python 3.5, Python 3.6

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue32014>
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