[Twisted-Python] Exit all threads upon KeyboardInterrupt

[Phil Mayers]

On 14/01/14 14:27, Dustin J. Mitchell wrote:
> There are two things wrong with your scenario.
>
> First, in any production or production-ready environment, your
> software needs to correctly handle stuck TCP connections.  With the
> proliferation of "smart" network equipment (session-tracking
> firewalls, etc.), this is much more common than it was five or ten
> years ago.  Some DBAPI backends are better about this than others -
> for example, MySQL-Python gets it right, but PyMySQL does not.

That is certainly a fine sentiment with which I agree in principle, but 
an ENORMOUSLY LARGE amount of (really very expensive and business 
critical) software doesn't handle this *at all* as anyone who runs a 
firewall in front of an e-Business app can tell you.

[A well known vendor whose name rhymes with a type of traditional small 
boat used extensively in the British Isles is a particular offender]

So if you're handling this correctly, give yourself a pat on the back - 
there is software costing millions a year in licence fees that assumes 
TCP is as reliable as CPU->CPU cache communications :o(

> 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.

I'm wondering if TCP keepalive isn't any use to you in this regard?

(and what do Mozilla do with Twisted? :o)