| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>, bttanakahbk <bttanakahbk(at)oss(dot)nttdata(dot)com>, Hamid Akhtar <hamid(dot)akhtar(at)gmail(dot)com>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Julien Rouhaud <rjuju123(at)gmail(dot)com>, "Tharakan, Robins" <tharar(at)amazon(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: track_planning causing performance regression |
| Date: | 2020-09-11 22:32:54 |
| Message-ID: | 20200911223254.isq7veutwxat4n2w@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
Hi,
On 2020-09-11 19:10:05 -0300, Alvaro Herrera wrote:
> Andres suggested in [1] to use atomics for the counters together with a
> single lwlock to be used in shared mode only. I didn't quite understand
> what the lwlock is *for*, but maybe you do.
>
> [1] https://postgr.es/m/20200629231015.qlej5b3qpfe4uijo@alap3.anarazel.de
Just to be clear - I am saying that in the first iteration I would just
straight up replace the spinlock with an lwlock, i.e. having many
lwlocks.
The piece about a single shared lwlocks is/was about protecting the set
of entries that are currently in-memory - which can't easily be
implemented just using atomics (at least without the risk of increasing
the counters of an entry since replaced with another query).
Greetings,
Andres Freund
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