Re: undetected deadlock in ALTER SUBSCRIPTION ... REFRESH PUBLICATION

Hi,

> I mean to commit the open transaction at the below place in
> wait_for_relation_state_change()
>
> wait_for_relation_state_change()
> {
> ...
> -- commit the xact
> WaitLatch();
> ...
> }
>
> Then start after the wait is over. This is just to test whether it
> improves the difference in regression test timing.

I tried the above approach and observed that the performance of this
approach is nearly same as the previous approach.

For Linux VM:
Summary | Subscription | 100 tables in pub | 1000 tables in pub
| Test (sec) | and Sub (sec) | and Sub (sec)
------------------------------------------------------------------------------
old patch | 107.4545 | 6.911 | 77.918
alternate | 108.3985 | 6.9835 | 78.111
approach

For Performance Machine:
Summary | Subscription | 100 tables in pub | 1000 tables in pub
| Test (sec) | and Sub (sec) | and Sub (sec)
------------------------------------------------------------------------------
old patch | 115.922 | 6.7305 | 81.1525
alternate | 115.8215 | 6.7685 | 81.2335
approach

I have attached the patch for this approach as 'alternate_approach.patch'.

Since the performance is the same, I think that the previous approach
is better. As in this approach we are using CommitTransactionCommand()
and StartTransactionCommand() inside a 'for loop'.

I also fixed the comment in previous approach and attached here as
'v2-0001-Deadlock-when-apply-worker-tablesync-worker-and-c.patch'

Thanks and Regards

Shlok Kyal