Re: TCP keepalive support for libpq

Fujii Masao <masao.fujii@gmail.com>

From: Fujii Masao <masao.fujii@gmail.com>

To: Peter Geoghegan <peter.geoghegan86@gmail.com>

Cc: pgsql-hackers@postgresql.org, Tollef Fog Heen <tollef.fog.heen@collabora.co.uk>, Robert Haas <robertmhaas@gmail.com>, Kevin Grittner <Kevin.Grittner@wicourts.gov>

Date: 2010-02-12T02:52:27Z

Lists: pgsql-hackers

On Fri, Feb 12, 2010 at 1:33 AM, Peter Geoghegan
<peter.geoghegan86@gmail.com> wrote:
> Why hasn't libpq had keepalives for years?

I guess that it's because keepalive doesn't work as expected
in some cases. For example, if the network outage happens
before a client sends some packets, keepalive doesn't work,
then it would have to wait for a long time until it detects
the outage. This is the specification of linux kernel. So
a client should not have excessive expectations of keepalive,
and should have another timeout like QueryTimeout of JDBC.

Regards,

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center