In general, if you have to call reactor.stop() manually like this in a script, you're probably doing too much manual fiddling with its lifecycle. I have not fully debugged this example, but I suspect it's just because the error is synchronous before the reactor starts.
However, rather than carefully managing the reactor's startup state like this where half your code runs synchronously before reactor startup, consider using <https://docs.twistedmatrix.com/en/stable/api/twisted.internet.task.html#react> instead and putting all your code (other than your imports) into your main function. This will result in far fewer confusing scenarios. Don't stop the reactor, just complete your coroutine and let `react()` shut it down for you when you're done. All that said: there are probably a bunch of improvements to the API and documentation that could make this easier, and the reactor's starting/stopping state shouldn't be such an opaque mess. It might be nice to eventually put it into an Automat state machine, for example, with some more explicit queries and fewer flags. So it's not like there's no work to be done here. But even if we did all that, the right way to write 99% of applications would still be to use something like a `twist` plugin, or a callable passed to `react`. Hope this helps, -g > On Jan 22, 2025, at 1:45 AM, Kirill Miazine <k...@krot.org> wrote: > > This has been driving me crazy for a while -- for some reason > reactor.stop() in the _error errback in example below raises > error.ReactorNotRunning. In order to stop the reactor, I have to do > reactor.callWhenRunning(reactor.stop) (or I did reactor.callLater(0, > ...) until I discovered callWhenRunning). > > In the example, I bind to a low port to make sure error is triggered. > > #!/usr/local/bin/python3 > > from twisted.internet import reactor, defer, protocol > from twisted.internet.protocol import Factory > from twisted.internet.endpoints import TCP4ServerEndpoint > > def _port(port): > print('got', port) > > def _error(err): > print('got err', err) > print('is reactor running?', reactor.running) > print('is reactor running?', (lambda: reactor.running)()) > reactor.stop() > # reactor.callWhenRunning(reactor.stop) > > d = TCP4ServerEndpoint(reactor, 123).listen(Factory()) > d.addCallback(_port) > d.addErrback(_error) > d.addErrback(print) > > reactor.run() > > > OTOH, in the following example reactor.stop() is stoppig the reactor > properly: > > #!/usr/local/bin/python3 > > from twisted.internet import reactor, defer > > def cb(res): > print('running?', reactor.running) > if res == 'bar': > raise Exception() > reactor.stop() > > def eb(err): > print('running?', reactor.running) > print(err) > reactor.stop() > > d = defer.Deferred() > d.addCallback(cb) > d.addErrback(eb) > > #reactor.callWhenRunning(d.callback, 'foo') > reactor.callWhenRunning(d.callback, 'bar') > > reactor.run() > > > Any ideas? > _______________________________________________ > Twisted mailing list -- twisted@python.org > To unsubscribe send an email to twisted-le...@python.org > https://mail.python.org/mailman3/lists/twisted.python.org/ > Message archived at > https://mail.python.org/archives/list/twisted@python.org/message/XK6XURKCRX44TLIY4C3RT3HZV5WYDA6C/ > Code of Conduct: https://twisted.org/conduct
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