Re: LWlock:LockManager waits

Hi James,

Take a look here, in the links you will find many info and real examples
for LockManager issues.

https://ardentperf.com/2024/03/03/postgres-indexes-partitioning-and-lwlocklockmanager-scalability/

Luiz

On Tue, Apr 9, 2024 at 4:08 AM James Pang <jamespang886(at)gmail(dot)com> 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
>
> Thanks,
>
> James
>