Horton

Re: 035_standby_logical_decoding unbounded hang

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Noah Misch <noah@leadboat.com>
Cc: pgsql-hackers@lists.postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2024-02-16T06:37:38Z
Lists: pgsql-hackers

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Hi,

On Thu, Feb 15, 2024 at 12:48:16PM -0800, Noah Misch wrote:
> On Wed, Feb 14, 2024 at 03:31:16PM +0000, Bertrand Drouvot wrote:
> > What about creating a sub, say wait_for_restart_lsn_calculation() in Cluster.pm
> > and then make use of it in create_logical_slot_on_standby() and above? (something
> > like wait_for_restart_lsn_calculation-v1.patch attached).
> 
> Waiting for restart_lsn is just a prerequisite for calling
> pg_log_standby_snapshot(), so I wouldn't separate those two.

Yeah, makes sense.

> If we're
> extracting a sub, I would move the pg_log_standby_snapshot() call into the sub
> and make the API like one of these:
> 
>   $standby->wait_for_subscription_starting_point($primary, $slot_name);
>   $primary->log_standby_snapshot($standby, $slot_name);
> 
> Would you like to finish the patch in such a way?

Sure, please find attached standby-slot-test-2-race-v2.patch doing so. I used
log_standby_snapshot() as it seems more generic to me.

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

Commits

  1. Back-patch test modifications that were done as part of b6df0798a5.

  2. Fix the intermittent buildfarm failures in 031_column_list.

  3. Fix test race between primary XLOG_RUNNING_XACTS and standby logical slot.

  4. Bound waits in 035_standby_logical_decoding.pl.