Fix remaining race condition with CLOG truncation and LISTEN/NOTIFY Previous commit fixed a bug where VACUUM would truncate the CLOG that's still needed to check the commit status of XIDs in the async notify queue, but as mentioned in the commit message, it wasn't a full fix. If a backend is executing asyncQueueReadAllNotifications() and has just made a local copy of an async SLRU page which contains old XIDs, vacuum can concurrently truncate the CLOG covering those XIDs, and the backend still gets an error when it calls TransactionIdDidCommit() on those XIDs in the local copy. This commit fixes that race condition.
To fix, hold the SLRU bank lock across the TransactionIdDidCommit() calls in NOTIFY processing. Per Tom Lane's idea. Backpatch to all supported versions. Reviewed-by: Joel Jacobson <[email protected]> Reviewed-by: Arseniy Mukhin <[email protected]> Discussion: https://www.postgresql.org/message-id/[email protected] Backpatch-through: 14 Branch ------ REL_16_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/44e8c60be66c7c174431c4cd7948c1ff015fe516 Modified Files -------------- src/backend/commands/async.c | 123 ++++++++++++++++++++++--------------------- 1 file changed, 62 insertions(+), 61 deletions(-)
