Re: [GENERAL] Is is safe to use SPI in multiple threads? - Mailing list pgsql-general

From Qiu Xiafei
Subject Re: [GENERAL] Is is safe to use SPI in multiple threads?
Date
Msg-id CA+ag+4PMreaDHehteaVPG0NEXKBzuRrF=xar+EBYO8NLg7u6JA@mail.gmail.com
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In response to [GENERAL] Is is safe to use SPI in multiple threads?  (Qiu Xiafei <qiuxiafei@gmail.com>)
List pgsql-general
Thanks for your reply.

Because of the one-backend-per-session concept of PG, I think I should bind one my DSL session to one bg worker only. It seems work. But is there a way to launch a bg worker when a new session starts, just like pg's per-session-backend do? Is it possible to run a bg worker for incoming sessions and to launch a new bg worker to handle the session when it comes?

On Saturday, December 10, 2016, Michael Paquier <michael.paquier@gmail.com> wrote:
On Fri, Dec 09, 2016 at 02:37:58PM -0800, Andres Freund wrote:
> On 2016-12-09 16:52:05 +0800, Qiu Xiafei wrote:
> > 1. Is there a way to use SPI in multi-thread style?
>
> No.
>
> > 2. Another option is to use libpq, like normal clients do. Is libpq as
> > efficient as SPI?
>
> No.

To give more details here, Postgres relies heavily on the fact that sessions
working in parallel on the backend should be done in separate processes,
like for transaction or snapshot handling.
--
Michael

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