Re: Fix locking issue with fixed-size stats template in injection_points
| От | wenhui qiu |
|---|---|
| Тема | Re: Fix locking issue with fixed-size stats template in injection_points |
| Дата | |
| Msg-id | CAGjGUAKX-q+TKi8eFEG3Nvc2g0GZsXQgZ=P07oy67XOYK0hbiQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Fix locking issue with fixed-size stats template in injection_points (Chao Li <li.evan.chao@gmail.com>) |
| Список | pgsql-hackers |
HI
This patch looks good to me.
The issue is clear: unlike other fixed-size stats kinds (archiver, bgwriter, checkpointer), the injection_points stats can be updated concurrently by multiple backends. Without synchronization, this can lead to inconsistent changecount state and assertion failures in pgstat_begin_changecount_write(), as shown in your reproduction.
The issue is clear: unlike other fixed-size stats kinds (archiver, bgwriter, checkpointer), the injection_points stats can be updated concurrently by multiple backends. Without synchronization, this can lead to inconsistent changecount state and assertion failures in pgstat_begin_changecount_write(), as shown in your reproduction.
Thanks
On Mon, Sep 29, 2025 at 3:29 PM Chao Li <li.evan.chao@gmail.com> wrote:
On Sep 29, 2025, at 14:27, Michael Paquier <michael@paquier.xyz> wrote:On Mon, Sep 29, 2025 at 09:46:05AM +0800, Chao Li wrote:I saw pg_state_begin_changecount_write() is called multiple places,
as you mention, for example bgwriter.
I've mentioned that in my first email, and put in details:
- pgstat_report_bgwriter() is called once, by the bgwriter.
- pgstat_report_checkpointer() is called three time, all by the
checkpointer.
- pgstat_report_archiver() is called twice, all by pgarch.c.
So all of them don't have a problem, two calls cannot happen
concurrently.
--
MichaelThanks for the clarification. Then the patch looks good to me.Best regards,
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