On Tue, 2024-04-09 at 11:07 +0800, James Pang wrote: > we found sometimes , with many sessions running same query "select ..." at the same time, saw many sessions waiting on "LockManager". for example, pg_stat_activity show. It's a production server, so no enable trace_lwlocks flag. could you direct me what's the possible reason and how to reduce this "lockmanager" lock? all the sql statement are "select " ,no DML. > > time wait_event count(pid) > 2024-04-08 09:00:06.043996+00 | DataFileRead | 42 > 2024-04-08 09:00:06.043996+00 | | 15 > 2024-04-08 09:00:06.043996+00 | LockManager | 31 > 2024-04-08 09:00:06.043996+00 | BufferMapping | 46 > 2024-04-08 09:00:07.114015+00 | LockManager | 43 > 2024-04-08 09:00:07.114015+00 | DataFileRead | 28 > 2024-04-08 09:00:07.114015+00 | ClientRead | 11 > 2024-04-08 09:00:07.114015+00 | | 11 That's quite obvious: too many connections cause internal contention in the database. Reduce the number of connections by using a reasonably sized connection pool. Yours, Laurenz Albe
