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From: Noah Misch <[email protected]>
To: Thomas Munro <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Windows socket problems, interesting connection to AIO
Date: Tue, 10 Sep 2024 15:40:52 -0700
Message-ID: <[email protected]> (raw)
In-Reply-To: <CA+hUKGLR10ZqRCvdoRrkQusq75wF5=vEetRSs2_u1s+FAUosFQ@mail.gmail.com>
References: <CA+hUKGLR10ZqRCvdoRrkQusq75wF5=vEetRSs2_u1s+FAUosFQ@mail.gmail.com>

On Mon, Sep 02, 2024 at 09:20:21PM +1200, Thomas Munro wrote:
> 2.  If a Windows client tries to send() and gets an ECONNRESET/EPIPE
> error, then the network stack seems to drop already received data, so
> a following recv() will never see it.  In other words, it depends on
> whether the application-level protocol is strictly request/response
> based, or has sequence points at which both ends might send().  AFAIK
> the main consequence for real users is that FATAL recovery conflict,
> idle termination, etc messages are not delivered to clients, leaving
> just "server closed the connection unexpectedly".

> The new thought I had about the second category of problem is: if you
> use asynchronous networking APIs, then the kernel *can't* throw your
> data out, because it doesn't even have it.  If the server's FATAL
> message arrives before the client calls send(), then the data is
> already written to user space memory and the I/O is marked as
> complete.

Good point.

> just wanted to share this observation.

Thanks for sharing that and the test program.

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