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Date: Thu, 10 May 2001 14:07:21 -0400
From: Christopher Faylor <cgf AT redhat DOT com>
To: cygwin AT cygwin DOT com
Cc: fred AT ontosys DOT com
Subject: Re: SIGTERM does not stop backend postgres processes immediately
Message-ID: <20010510140721.F12136@redhat.com>
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In-Reply-To: <20010510123628.A48047@enteract.com>; from fred@ontosys.com on Thu, May 10, 2001 at 12:36:28PM -0500

On Thu, May 10, 2001 at 12:36:28PM -0500, Fred Yankowski wrote:
>On Thu, May 10, 2001 at 12:31:02PM -0400, Christopher Faylor wrote:
>> Remember this?
>> >Unfortunately, blocking recv() calls are not interruptible on Windows.
>> >I'm not aware of any mechanism for allowing this.
>
>Some research led me to believe that closesocket() could unblock a
>Win32 recv() call.
>
>> What do you think a signal handler does?  It would need to interrupt
>> a blocking recv() to work, wouldn't it?
>
>Are you saying that a blocking recv() _must_ never be interrupted,

I didn't say "must".  I said "can't".

>even if a mechanism exists that would make that possible?

What mechanism is this?  You have already demonstrated that you can't
use Cygwin signals to interrupt a recv.  You seem to be using circular
reasoning:

"Hmm.  I'm having problems with getting signals to interrupt a recv()
call.  Chris says that recv calls can't be interrupted but someone else
says that closesocket works.  So, I know! I'll use a *signal* to
interrupt the recv call and close the socket!"

Perhaps this would work if you used another thread but there is no
mechanism in cygwin for doing this currently and I really doubt that
closing a socket is the right solution for dealing with this problem.

>If so, what is the basis for that decision?  The recv() specified by
>the Open Group [1] seems to allow for an EINTR error case.

I'll bet the the Open Group would imply that a signal does not close
a socket if you are blocked in a recv() call, too.

I don't know why you are getting the impression that I'm passing down
an edict.  I'm always open to methods for getting Cygwin to work
more like UNIX.  I don't see how closing the socket can achieve this
goal, even if you could make it work.

cgf

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