You're absolutely right. I wasn't arguing with you, but with JP :) Dustin
On Tue, Jan 14, 2014 at 2:06 PM, Glyph Lefkowitz <gl...@twistedmatrix.com> wrote: > On Jan 14, 2014, at 6:27 AM, Dustin J. Mitchell <dus...@v.igoro.us> wrote: > > Second, this has nothing whatsoever to do with whether the I/O is > blocking or not. Twisted apps can and, believe me from experience, do > suffer from stuck TCP connections. Sure, the wasted resources in this > case are smaller (just a file descriptor, not a thread), but the user > experience is the same (part of the application hangs irreversibly). > In fact, this is about the only thing the manhole is used for at > Mozilla: running `os.close` on stuck fd's. > > > The lack of 'abortConnection' was a pretty serious design flaw in Twisted's > transport interface initially, but that's been resolved for quite some time > now. It should be possible to handle this at the application level on a > per-connection basis quite gracefully now. > > I mean, your point is correct; you can certainly have "stuck" event sources > in Twisted too, without any threads. And without any intervention it > results in exactly the same bad user experience. I've certainly seen it > myself. > > However, intervention is easier than with a stuck thread. You can't > interrupt an arbitrary thread; you don't know and can't tell what it is > doing without pretty invasive debugging instrumentation. And, as you note, > even before the advent of abortConnection, an os.close() could easily deal > with a stuck async FD on a per-connection basis, without need to bring the > entire process down. > > Finally, we have abortConnection now, so my main point stands; the point was > not "never call os._exit" but rather "if you have to call os._exit, there's > a bug". The same is true here: if you have to manhole into your server to > call os.close, there's a bug in your application where it's not timing > something out and freeing a resource it otherwise could be freeing. > > Unless your contention is that there are no bugs in buildbot? ;-) > > -glyph > > > _______________________________________________ > Twisted-Python mailing list > Twisted-Python@twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python > _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
