On Mon, Feb 22, 2021 at 7:52 AM Andres Freund <and...@anarazel.de> wrote: > > On 2021-02-21 19:05:03 +0100, Daniele Varrazzo wrote: > > One of the HikariCP configuration parameters is "maxLifetime", whose > > description is: "This property controls the maximum lifetime of a > > connection in the pool. [...] **We strongly recommend setting this > > value, and it should be several seconds shorter than any database or > > infrastructure imposed connection time limit.**" (bold is theirs, > > default value is 30 mins). > > > > When discussing the pool features in the psycopg mailing list someone > > pointed out "what is the utility of this parameter? connections don't > > rot, do they?" > > > > Hikari is a generic connection pool, not one specific for Postgres. So > > I'm wondering: is there any value in periodically deleting and > > recreating connections for a Postgres-specific connection pool? Is a > > MaxLifetime parameter useful? > > It's extremely useful.
+1, I multiple times had to rely on similar cleanup in other poolers. > If your pooler is used in a large application > with different "parts" or your application uses schema based > multi-tenancy or such, you can end up with the various per-connection > caches getting very large without providing much benefit. Unfortunately > we do not yet have effective "pressure" against that. Similarly, if you > have an application using prepared statements you can end up with enough > prepared statements for that to be a memory usage issue. And in some case negative cache entries can be a problem too.
