[Twisted-Python] Graceful shutdown of twistd application

[Fabio Sangiovanni]

Hi,

I just wanted to give an update about the way I got it, in case this could
be useful for somebody.
I essentially inherited from service.MultiService like this:

class GracefulMultiService(service.MultiService):

    def stopService(self):
        d = defer.succeed(None)
        d.addCallback(self._wait_for_your_cleanup_code_to_complete)
        d.addCallback(lambda _: self)
        d.addCallback(service.MultiService.stopService)
        return d

  @defer.inlineCallbacks
  def _wait_for_your_cleanup_code_to_complete(self):
        [...]
        yield sleep(10)  # cleanup code example


def sleep(secs):
    d = defer.Deferred()
    reactor.callLater(secs, d.callback, None)
    return d




Thanks again for your help!


On Thu, Sep 4, 2014 at 2:55 PM, <exarkun at twistedmatrix.com> wrote:

> On 12:36 pm, sangiovanni at nweb.it wrote:
>
>> On Thu, Sep 4, 2014 at 2:02 PM, <exarkun at twistedmatrix.com> wrote:
>>
>>>
>>>
>>> You said before shutdown triggers are too late but you didn't say why. I
>>> think that's based on a misunderstanding - but if not, then explain why
>>> it
>>> doesn't work for your scenario.
>>>
>>
>> Hi, thanks for your reply.
>>
>> I've tried the following:
>>
>> def sleep(secs):
>>    log.msg('from within trigger')
>>    d = defer.Deferred()
>>    reactor.callLater(secs, d.callback, None)
>>    return d
>>
>> reactor.addSystemEventTrigger('before', 'shutdown', sleep, 10)
>>
>
> All 'before' trigger are run concurrently.  If you're using `Application`
> then your `sleep` trigger runs concurrently with the application's
> `stopService` trigger (because `Application` has its stopService added as
> another 'before' shutdown' trigger alongside yours).
>
> If you want to delay your application shutdown, you need to cooperate a
> little more closely with it.  Either attach your application shutdown code
> as a callback to the sleep Deferred or move the sleep into the stopService
> implementation of one of the services on your application and trigger the
> remaining stopService calls (eg the stopService call on the MultiService
> you mentioned) when the sleep Deferred fires there.
>
> Jean-Paul
>
>
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>


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