Re: Race conditions in 019_replslot_limit.pl

Hi,

On 2022-02-16 22:11:30 -0500, Tom Lane wrote:
> So (a) it broke around 48 hours ago, which is already a useful
> bit of info

Indeed. 2f6501fa3c54bbe4568e3bcccd9a60d26a46b5ee seems like the obvious commit
to blame.

We document before_shmem_exit hooks as
/*
* Call before_shmem_exit callbacks.
*
* These should be things that need most of the system to still be up and
* working, such as cleanup of temp relations, which requires catalog
* access; or things that need to be completed because later cleanup steps
* depend on them, such as releasing lwlocks.
*/
and several before_shmem_exit callbacks use lwlocks.

But right now I'm not seeing what prevents us from throwing a FATAL error
while holding an lwlock?

> , and (b) your animals seem far more susceptible than
> anyone else's. Why do you suppose that is?

Flaviventris, serinus use the newest snapshot of gcc available in debian, one
with -O0, the other with O3.

desmoxytes, idiacanthus, komodoensis all have JIT forced for every query.

They all run on the same host - looking at stats it doesn't look crazily
overcommitted or such. But it might have more scheduler variance than most?

Greetings,

Andres Freund