Re: Let's make PostgreSQL multi-threaded

On Wed, Jun 7, 2023 at 06:38:38PM +0530, Ashutosh Bapat wrote:
> With multiple processes, we can use all the available cores (at least
> theoretically if all those processes are independent). But is that
> guaranteed with single process multi-thread model? Google didn't throw
> any definitive answer to that. Usually it depends upon the OS and
> architecture.
>
> Maybe a good start is to start using threads instead of parallel
> workers e.g. for parallel vacuum, parallel query and so on while
> leaving the processes for connections and leaders. that itself might
> take significant time. Based on that experience move to a completely
> threaded model. Based on my experience with other similar products, I
> think we will settle on a multi-process multi-thread model.

I think we have a few known problem that we might be able to solve
without threads, but can help us eventually move to threads if we find
it useful:

1) Use threads for background workers rather than processes
2) Allow sessions to be stopped and started by saving their state

Ideally we would solve the problem of making shared structures
resizable, but I am not sure how that can be easily done without
threads.

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Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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