Re: SO_KEEPALIVE

On E, 2005-05-16 at 19:22 +0200, Dennis Bjorklund wrote:
> On Mon, 16 May 2005, Tom Lane wrote:
>
> > > How come we don't set SO_KEEPALIVE in libpq?
> > > Is there any reason why we wouldn't want it on?
> >
> > Is there any reason we *would* want it on? The server-side keepalive
> > should be sufficient to get whatever useful impact it might have.
>
> Wouldn't the client also want to know that the server is not there
> anymore? I talked to Gaetano Mendola (I think, but you never know on irc
> :-) and he had some clients that had been hanging around for 3 days after
> the server had been down and later up again (stuck in recv).

"stuck in recv" is symptom of a reconnect bug when libpq first tries to
test for a SSL connection but the connect has already gone away.
(search for "[HACKERS] oldish libpq bug still in RC2" in lists)
Tom fixed it in no time once I showed him where to look and provided a
test case. It should be fixed in 8.0.

I don't know if the fix was backported to older libpq versions as well.

> Server-side keepalive is enough for the server to clean up when clients
> disapears, but this do nothing to help clients detect that the server is
> gone. So I don't see what server side keepalive has to do with it.

--
Hannu Krosing <hannu(at)tm(dot)ee>