[Twisted-Python] twisted and threading

twisted-10152003 at atlas.lcs.mit.edu twisted-10152003 at atlas.lcs.mit.edu
Tue Aug 17 22:18:51 EDT 2004

Christopher Armstrong [radeex at gmail.com] wrote:
>On Tue, 17 Aug 2004 20:34:44 -0400, twisted-10152003 at atlas.lcs.mit.edu
><twisted-10152003 at atlas.lcs.mit.edu> wrote:
>> I wrapped a c library using swig and was hoping to make use of it in
>> a twisted server I am writing.  The issue is that the c library
>> fundamentally blocks waiting for input that may never come.  Is
>> there a way from twisted to deal with this cleanly within the
>> framework?
>> I.e. some combination of adding a reactor.addSystemEventTrigger event
>> and calling reactor.threadpool.stop seem like it should work but
>> I haven't had any luck yet.
>Try twisted.internet.threads.deferToThread(myBlockingCall) -->

Ah, but that doesn't work.  As I stated the c library (not mine) calls
potentially block forever (or at least longer than I want to wait to
shutdown the twisted server).  The thread created by deferTothread may
never complete which makes shutting down the server gracefully
impossible (or so I thought?).

>Geeze, where'd you come up with that stuff? Accessing
>reactor.threadpool directly is Really Bad. I hope there's no example
>code or documentation that refers to that.

:) Ah the hazards of attempting to read documentation and mailing-lists
before posting...

The threadpool and a link to its interface are mentioned on the primary
threading howto.  No mention of "Really Bad" there. 


And other posts about threading on this mailing list mentioned
looking at twisted.enterprise.adbapi which is where
reactor.addSystemEventTrigger ideas came from.  

Incidentally, I am happy to help update documentation if I can
figure out the right ways to do things. :)

Thanks for your rapid response.

Steve Bauer

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