Re: Assertion failure in SnapBuildInitialSnapshot()

On Tue, Jan 31, 2023 at 11:12 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Mon, Jan 30, 2023 at 9:41 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> I've attached patches for HEAD and backbranches. Please review them.
>

Shall we add a comment like the one below in
ReplicationSlotsComputeRequiredXmin()?
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index f286918f69..e28d48bca7 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -840,6 +840,13 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)

Assert(ReplicationSlotCtl != NULL);

+ /*
+ * It is possible that by the time we compute the agg_xmin
here and before
+ * updating replication_slot_xmin, the CreateInitDecodingContext() will
+ * compute and update replication_slot_xmin. So, we need to acquire
+ * ProcArrayLock here to avoid retreating the value of
replication_slot_xmin.
+ */
+

--
With Regards,
Amit Kapila.