Re: MultiXact\SLRU buffers configuration

> 10 нояб. 2020 г., в 05:13, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> написал(а):
> After the issue reported in [1] got fixed, I've restarted the multi-xact
> stress test, hoping to reproduce the issue. But so far no luck :-(

Tomas, many thanks for looking into this. I figured out that to make multixact sets bigger transactions must hang for a while and lock large set of tuples. But not continuous range to avoid locking on buffer_content.
I did not manage to implement this via pgbench, that's why I was trying to hack on separate go program. But, essentially, no luck either.
I was observing something resemblant though

пятница, 8 мая 2020 г. 15:08:37 (every 1s)

pid | wait_event | wait_event_type | state | query
-------+----------------------------+-----------------+--------+----------------------------------------------------
41344 | ClientRead | Client | idle | insert into t1 select generate_series(1,1000000,1)
41375 | MultiXactOffsetControlLock | LWLock | active | select * from t1 where i = ANY ($1) for share
41377 | MultiXactOffsetControlLock | LWLock | active | select * from t1 where i = ANY ($1) for share
41378 | | | active | select * from t1 where i = ANY ($1) for share
41379 | MultiXactOffsetControlLock | LWLock | active | select * from t1 where i = ANY ($1) for share
41381 | | | active | select * from t1 where i = ANY ($1) for share
41383 | MultiXactOffsetControlLock | LWLock | active | select * from t1 where i = ANY ($1) for share
41385 | MultiXactOffsetControlLock | LWLock | active | select * from t1 where i = ANY ($1) for share
(8 rows)

but this picture was not stable.

How do you collect wait events for aggregation? just insert into some table with cron?

Thanks!

Best regards, Andrey Borodin.