[Twisted-Python] pb help needed.

[Syver Enstad]

Syver Enstad <syver at inout.no> writes:

> I have a bug in my woven application which manifests itself as
> win32select failing after doing many http requests. The error is the
> constant WSAENOBUFS and I it seems pretty likely that this is caused
> by some socket related resource leaking for each request I make. This
> hypothesis is further supported by observing that a host of
> pb.ClientFactory instances are stopped when shutting down the
> application after it crashes. This seems strange to me as I am
> thorough in shutting down the connector after every request is
> finished.
> 
> Turning to that trusty friend printf style debugging, shows that the
> PBClientFactory is stopped correctly when performing requests to pages
> that use the referenceable and wait for it's deferred's to
> complete. There are two cases when it doesn't stop. 
> 
> The first is when I press reload quickly a number of times. Then I
> just see start messages because my request finish method is not called
> (it is a callback to the deferred returned by request.notifyFinish()).
> 
> The second case is when I call disconnect on the connector before it's
> deferred has been realised. I see in the log the following pattern:
> Starting pb.PBClientFactory, disconnect and then the attached event,
> stopping factory is not called at all. After stepping I see that
> disconnect doesn't do anything when it is called before the connection
> has been realized.
> 
> So I have a bug, and it's in my code. My question is how does one
> manage pb resources correctly and easily (I don't worry about
> performance just yet) when each user needs to have it's own
> connection?

Here is what I have come up with so far. It doesn't solve the problem
where I don't get the request finish callback, but seems to be able to
disconnect even if not connected when disconnect is called.

class MyPBClientFactory(pb.PBClientFactory):
    def disconnect(self):
        if not self._broker:
            deferred = self.getRootObject()
            deferred.addCallback(
                lambda unused: pb.PBClientFactory.disconnect(self))
        else:
            pb.PBClientFactory.disconnect(self)