| From: | Anthonin Bonnefoy <anthonin(dot)bonnefoy(at)datadoghq(dot)com> |
|---|---|
| To: | Kirill Reshke <reshkekirill(at)gmail(dot)com> |
| Cc: | Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Don't keep closed WAL segment in page cache after replay |
| Date: | 2026-02-18 09:51:59 |
| Message-ID: | CAO6_Xqric0=7TVC-dLySU6_mtG3ie8kJY=87EjDeYjqGc3uNNA@mail.gmail.com |
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| Lists: | pgsql-hackers |
Thanks for the review!
On Tue, Feb 17, 2026 at 9:38 AM Kirill Reshke <reshkekirill(at)gmail(dot)com> wrote:
> This does not immediately strike me as good reasoning. We have, for
> example, pg_stat_get_wal_senders (or WalSndInitStopping from
> walsenders.h) function which accesses exactly WalSndCtl->walsnds.
> Why don't we simply have another utility function that will return the
> number of active walsenders?
That's true it is an option. I've switched to this approach and
created a WalSndRunning. We only need to know if there's at least one
wal sender running, no need to have a precise number.
I've also added StandbyMode as a condition to restrict this to
replicas. XLogPageRead may be used by the primary when starting up,
and will likely re-read the WAL so releasing cached pages should be
avoided on the primary.
| Attachment | Content-Type | Size |
|---|---|---|
| v3-0001-Don-t-keep-closed-WAL-segments-in-page-cache-afte.patch | application/octet-stream | 3.6 KB |
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