RE: Timeout parameters

From: "Nagaura, Ryohei" <nagaura(dot)ryohei(at)jp(dot)fujitsu(dot)com>
To: "MikalaiKeida(at)ibagroup(dot)eu" <MikalaiKeida(at)ibagroup(dot)eu>
Cc: "AYahorau(at)ibagroup(dot)eu" <AYahorau(at)ibagroup(dot)eu>, 'Fabien COELHO' <coelho(at)cri(dot)ensmp(dot)fr>, "Jamison, Kirk" <k(dot)jamison(at)jp(dot)fujitsu(dot)com>, "'Michael Paquier'" <michael(at)paquier(dot)xyz>, "'pgsql-hackers(at)postgresql(dot)org'" <pgsql-hackers(at)postgresql(dot)org>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>
Subject: RE: Timeout parameters
Date: 2019-03-13 07:46:23
Message-ID: EDA4195584F5064680D8130B1CA91C453F39CB@G01JPEXMBYT04
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Hello Mikalai-san.

> From: MikalaiKeida(at)ibagroup(dot)eu <MikalaiKeida(at)ibagroup(dot)eu>
> The main idea of my comment was to avoid handling logical errors ( "client-side
> timeout") in advance to the detection of network problems!!!!
> Therefore, I suggested setting "client-side timeout" greater of equal to the
> TCP_USER_TIMEOUT or note about it in the documentation.
I have caught up with your intension. You have a point! Thank you.

> I'm afraid to be mistaken but I think that when network is alive it means that OS
> does not hang.
> I think that it is a responsibility of the OS kernel to manage network connections.
> Keep_alive mechanism checks a network state by exchanging data between
> client's and server's OS kernels. I think the same procedure is used in
> TCP_USER_TIMEOUT mechanism. So, when keep_alive and
> TCP_USER_TIMEOUT say that network works correct, it means that kernels of
> client and server do not hang. On the other hand it does not guarantee that
> PostgreSQL server is not hang. "client-side timeout" should handle this problem
> when network problem was not detected.
Thank you for your kind explain.

Best regards,
---------------------
Ryohei Nagaura

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