Re: close() of active socket does not work on FreeBSD 6

On Thu, 21 Dec 2006, John-Mark Gurney wrote:

Daniel Eischen wrote this message on Thu, Dec 21, 2006 at 22:35 -0500:
On Thu, 21 Dec 2006, John-Mark Gurney wrote:

I used to expect something similar w/ an kqueue based event driven
web server, and found that I had bugs due to assuming that I could
close it whenever I want... What happens if you close the fd between
the time select returns and you process it? What happens if the fd
gets closed, and another thread (or an earlier fd that accepts
connections) reuses that fd? And then youre state machine isn't read
to get an event since it isn't suppose to get one yet...

The kernel isn't buggy wrt closing a fd when another thread is using
it, it's the program that's buggy...

I agree also, but hanging without return isn't very detectable.

It's a lot more detectable than working 99% more of the time and
failing when things get correupted due to a race.. :)

I dunno, I think returning an appropriate error on the actual
call(s) that are problematic is easier to detect than trying
to figure out just what is causing the hang, corruption,
whatever. Perhaps I mean "debug" instead of "detect".

The best thing to do is to tell the programmer that he is doing
something stupid, and returning with an error is the way that
it is typically done. Solaris seems to have jumped through

As long as it's EDOOFUS... I don't see any other error that would
be approriate...

EBADF. That's what Solaris returns and makes more sense
to me.

some hoops to achieve this behavior, so I doubt it is without
merit. OTOH, I'm not going to argue that it is one of the
more important things we should be worried about ;-)

As long as it doesn't cost much more to do it... Hanging is just as
good of an indication as returning an error... And I'd say it's better
as it forces the buggy software to be fixed as opposed to simply ignoring
the error which is likely what the programmer will do...

Yes, unfortunately, ignoring the error would probably happen
a lot.

--
DE
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