On 09/01/2026 00:20, Nathan Bossart wrote:
On Thu, Jan 08, 2026 at 09:57:38PM +0200, Heikki Linnakangas wrote:
* It makes it consistent with background workers. When a background worker
exits, the postmaster sends the signal to the launching process (if
requested).
I've wondered about making autovacuum workers proper background workers.
Yeah, me too...
I'm a little surprised it wasn't done this way to begin with, so I wonder if
I'm missing something?
This code dates back to commit e2a186b03c. I skimmed through the nearby
thread [0] and didn't immediately notice any discussion about this. My
guess is that it seemed simpler to directly alert the launcher, since it's
the one that needs to take action.
[0] https://postgr.es/m/flat/20070404233954.GK19251%40alvh.no-ip.org
Thanks for checking. I suspect we wanted to keep postmaster as dumb as
possible, having all logic in the child process if at all possible. But
we perhaps went a little overboard with that; signaling child processes
seems squarely like postmaster's core business.
On 09/01/2026 10:27, li carol wrote:
On Thu, Jan 8, 2026 at 11:57 AM Heikki Linnakangas <[email protected]> wrote:
When an autovacuum worker exits, ProcKill() sends SIGUSR2 to the
launcher. I propose moving that responsibility to the postmaster, because:
* It's simpler IMHO
* The postmaster is already responsible for sending the signal if
fork() fails
* It makes it consistent with background workers. When a background
worker exits, the postmaster sends the signal to the launching process
(if requested).
* Postmaster doesn't need to worry about sending the signal to the
wrong process if the launcher's PID is reused, because it always has
up-to-date PID information, because the launcher is postmaster's child
process. That risk was negligible to begin with, but this eliminates
completely, so we don't need the comment excusing it it anymore.
It sounds reasonable to me too. +1.
I have completed the testing for this patch with a focus on the signaling logic
from postmaster to launcher.
...
This confirms that the postmaster successfully notifies the launcher and the
worker slot is freed appropriately before the notification.
The patch looks correct and robust. +1 from my side.
Committed, thanks for the reviews and testing!
- Heikki
