Hoi Tom, On Mon, 16 Sep 2019 at 15:33, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Martijn van Oosterhout <klep...@gmail.com> writes: > > I think I like the idea of having SignalBackend do the waking up a > > slow backend but I'm not enthused by the "lets wake up (at once) > > everyone that is behind". That's one of the issues I was explicitly > > trying to solve. If there are any significant number of "slow" > > backends then we get the "thundering herd" again. > > But do we care? With asyncQueueAdvanceTail gone from the listeners, > there's no longer an exclusive lock for them to contend on. And, > again, I failed to see any significant contention even in HEAD as it > stands; so I'm unconvinced that you're solving a live problem.
You're right, they only acquire a shared lock which is much less of a problem. And I forgot that we're still reducing the load from a few hundred signals and exclusive locks per NOTIFY to perhaps a dozen shared locks every thousand messages. You'd be hard pressed to demonstrate there's a real problem here. So I think your patch is fine as is. Looking at the release cycle it looks like the earliest either of these patches will appear in a release is PG13, right? Thanks again. -- Martijn van Oosterhout <klep...@gmail.com> http://svana.org/kleptog/
