pgsql: Fix remaining race condition with CLOG truncation and LISTEN/NOT
| От | Heikki Linnakangas |
|---|---|
| Тема | pgsql: Fix remaining race condition with CLOG truncation and LISTEN/NOT |
| Дата | |
| Msg-id | E1vJGKc-006Hex-2q@gemulon.postgresql.org обсуждение исходный текст |
| Список | pgsql-committers |
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 <joel@compiler.org> Reviewed-by: Arseniy Mukhin <arseniy.mukhin.dev@gmail.com> Discussion: https://www.postgresql.org/message-id/2759499.1761756503@sss.pgh.pa.us Backpatch-through: 14 Branch ------ REL_14_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/c2e58c0711fe76daef47c7e85a770fc93156b90f Modified Files -------------- src/backend/commands/async.c | 123 ++++++++++++++++++++++--------------------- 1 file changed, 62 insertions(+), 61 deletions(-)
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