Horton

Re: Track the amount of time waiting due to cost_delay

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: "Imseih (AWS), Sami" <simseih@amazon.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Robert Haas <robertmhaas@gmail.com>
Date: 2024-08-20T12:48:29Z
Lists: pgsql-hackers

Commits

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  1. Add delay time to VACUUM/ANALYZE (VERBOSE) and autovacuum logs.

  2. Add cost-based vacuum delay time to progress views.

  3. Add is_analyze parameter to vacuum_delay_point().

  4. Refresh cost-based delay params more frequently in autovacuum

Attachments

Hi,

On Mon, Jul 01, 2024 at 04:59:25AM +0000, Bertrand Drouvot wrote:
> Hi,
> 
> On Fri, Jun 28, 2024 at 08:07:39PM +0000, Imseih (AWS), Sami wrote:
> > > 46ebdfe164 will interrupt the leaders sleep every time a parallel workers reports
> > > progress, and we currently don't handle interrupts by restarting the sleep with
> > > the remaining time. nanosleep does provide the ability to restart with the remaining
> > > time [1], but I don't think it's worth the effort to ensure more accurate
> > > vacuum delays for the leader process. 
> > 
> > After discussing offline with Bertrand, it may be better to have 
> > a solution to deal with the interrupts and allows the sleep to continue to
> > completion. This will simplify this patch and will be useful 
> > for other cases in which parallel workers need to send a message
> > to the leader. This is the thread [1] for that discussion.
> > 
> > [1] https://www.postgresql.org/message-id/01000190606e3d2a-116ead16-84d2-4449-8d18-5053da66b1f4-000000%40email.amazonses.com
> > 
> 
> Yeah, I think it would make sense to put this thread on hold until we know more
> about [1] (you mentioned above) outcome.

As it looks like we have a consensus not to wait on [0] (as reducing the number
of interrupts makes sense on its own), then please find attached v4, a rebase
version (that also makes clear in the doc that that new field might show slightly
old values, as mentioned in [1]).

[0]: https://www.postgresql.org/message-id/flat/01000190606e3d2a-116ead16-84d2-4449-8d18-5053da66b1f4-000000%40email.amazonses.com
[1]: https://www.postgresql.org/message-id/ZruMe-ppopQX4uP8%40nathan

Regards,

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