Re: old_snapshot_threshold bottleneck on replica

On Tue, 24 Jan 2023 at 18:46, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

>
> (1) that mutex also protects something else and the existing comment
> is wrong, or
>
> (2) the mutex should have been removed but the patch neglected to do so, or
>
> (3) the mutex is still needed for some reason, in which case either
> (3a) the patch isn't actually safe or (3b) the patch needs comments to
> explain what the new synchronization model is.
>
> Yes, you're absolutely right. And my first intention was to remove this
mutex completely.
But in TransactionIdLimitedForOldSnapshots these variable is using
conjointly. So, I'm not
sure, is it completely safe to remove mutex. Actually, removing mutex and
switch to atomics
was my first choice. I've run all the tests and no problems were found.
But, at that time I choose
to be more conservative. Anyway, here is the new variant.

--
Best regards,
Maxim Orlov.