Re: [PATCH] Reuse Workers and Replication Slots during Logical Replication

On Thu, Feb 2, 2023 at 9:18 AM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
>
> Hi Melih,
> I think I am able to identify the root cause. It is not memory
> corruption, but the way origin-names are stored in system-catalog
> mapped to a particular relation-id before even those are created.
>

Apart from the problem mentioned in my earlier email, I think there is
one more issue here as seen by the same assert causing testcase. The
'lastusedid' stored in system-catalog kept on increasing w/o even slot
and origin getting created. 2 workers worked well with
max_replication_slots=2 and then since all slots were consumed 3rd one
could not create any slot and exited but it increased lastusedid. Then
another worker came, incremented lastusedId in system-catalog and
failed to create slot and exited and so on. This makes lastUsedId
incremented continuously until you kill the subscriber or free any
slot used previously. If you keep subscriber running long enough, it
will make lastUsedId go beyond its limit.
Shouldn't lastUsedId be incremented only after making sure that worker
has created a slot and origin corresponding to that particular
rep_slot_id (derived using lastUsedId). Please let me know if my
understanding is not correct.

thanks
Shveta