Re: Keepalives win32

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: "Magnus Hagander" <magnus(at)hagander(dot)net>, "Pavel Golub" <pavel(at)gf(dot)microolap(dot)com>, "Bruce Momjian" <bruce(at)momjian(dot)us>, "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Keepalives win32
Date: 2010-06-30 15:46:48
Message-ID: 11212.1277912808@sss.pgh.pa.us
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"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> I also think we may want to suggest that for most environments,
> people may want to change these settings to something more
> aggressive, like a 30 to 120 second initial delay, with a 10 or 20
> second retry interval. The RFC defaults seem approximately right
> for a TCP connection to a colony on the surface of the moon, where
> besides the round trip latency of 2.5 seconds they might have to pay
> by the byte.

Well, the RFCs were definitely written at a time when bandwidth was a
lot more expensive than it is today.

> In other words, it is *so* conservative that I have
> trouble seeing it ever causing a problem compared to not having
> keepalive enabled, but it will eventually clean things up.

Yes. This is a large part of the reason why I think it's okay for us to
turn libpq keepalive on by default in 9.0 --- the default parameters for
it are so conservative as to be unlikely to cause trouble. If Windows
isn't using RFC-equivalent default parameters, that seems like a good
reason to disregard the system settings and force use of the RFC values
as defaults.

regards, tom lane

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