| From: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Maksim Milyutin <milyutinma(at)gmail(dot)com>, "tsunakawa(dot)takay(at)fujitsu(dot)com" <tsunakawa(dot)takay(at)fujitsu(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Tatsuo Ishii <ishii(at)sraoss(dot)co(dot)jp>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Zhihong Yu <zyu(at)yugabyte(dot)com> |
| Subject: | Re: Add client connection check during the execution of the query |
| Date: | 2022-01-14 06:30:07 |
| Message-ID: | CA+hUKGL1uR0qKy3Hy8-9aFU=jxcGedaKqYTx_gRdyRg0p7cKGw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Jan 14, 2022 at 4:35 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> The more I think about it, the less I see why we *ever* need to re-arm the
> latch in pq_check_connection() in this approach. pq_check_connection() is only
> used from from ProcessInterrupts(), and there's plenty things inside
> ProcessInterrupts() that can cause latches to be reset (e.g. parallel message
> processing causing log messages to be sent to the client, causing network IO,
> which obviously can do a latch reset).
Thanks for the detailed explanation. I guess I was being overly
cautious and a little myopic, "leave things exactly the way you found
them", so I didn't have to think about any of that. I see now that
the scenario I was worrying about would be a bug in whatever
latch-wait loop happens to reach this code. Alright then, here is
just... one... more... patch, this time consuming any latch that gets
in the way and retrying, with no restore.
| Attachment | Content-Type | Size |
|---|---|---|
| v7-0001-Add-WL_SOCKET_CLOSED-for-socket-shutdown-events.patch | text/x-patch | 7.8 KB |
| v7-0002-Use-WL_SOCKET_CLOSED-for-client_connection_check_.patch | text/x-patch | 5.1 KB |
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