Re: [PATCH] Refactoring of LWLock tranches

On November 19, 2015 8:09:38 AM PST, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>On Thu, Nov 19, 2015 at 9:04 AM, Ildus Kurbangaliev
><i(dot)kurbangaliev(at)postgrespro(dot)ru> wrote:
>> The moving base tranches to shared memory has been discussed many
>times.
>> The point is using them later in pg_stat_activity and other
>monitoring
>> views.
>
>I'm not in agreement with this idea. Actually, I'd prefer that the
>tranches live in backend-private memory, not shared memory, so that we
>could for example add backend-local counters to them if desired.

I don't buy that argument. It'd be nearly trivial to have a backend_tranchestats array, indexed by the tranche id, for such counters.

It's really not particularly convenient to allocate tranches right now. You have to store at least the identifier in shared memory and then redo the registration in each process. Otherwise some processes can't identify them. Which of rather inconvenient of you want to register some at runtime

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