[freetds] [PATCH] Configurable TCP KeepAlives

Jackson, Craig (Gale) Craig.Jackson at cengage.com
Mon Aug 11 20:18:50 EDT 2008


FYI, the default timeouts in Berkeley-derived code are much greater than
a minute.  As I recall, there was a doubling backoff until it got to 64
seconds, and then it tried 8 times at 64 seconds.  It came to 10 minutes
or so.

I'm sure that this code has changed over the years, and there are TCP stacks
not based on BSD, but it still takes quite a while for an active TCP connection
to time out on most systems.

(Timeouts on the initial connect are typically shorter.  The historical
BSD time is around 75 seconds.)

Craig

-----Original Message-----
From: freetds-bounces at lists.ibiblio.org [mailto:freetds-bounces at lists.ibiblio.org] On Behalf Of James K. Lowden
Sent: Monday, August 11, 2008 6:53 PM
To: FreeTDS Development Group
Subject: Re: [freetds] [PATCH] Configurable TCP KeepAlives


. . .

>1.  If a query is being sent, the ACK packet will not be received,
>eventually resulting in a write(2) failure.  That timeout is based on RTT
>and will typically be under a minute.

. . .

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