Fix race condition at backend exit when deleting element in syncrep queue When a backend exits, it gets deleted from the syncrep queue if present. The queue was checked without SyncRepLock taken in exclusive mode, so it would have been possible for a backend to remove itself after a WAL sender already did the job. Fix this issue based on a suggestion from Fujii Masao, by first checking the queue without the lock. Then, if the backend is present in the queue, take the lock and perform an additional lookup check before doing the element deletion.
Author: Dongming Liu Reviewed-by: Kyotaro Horiguchi, Fujii Masao, Michael Paquier Discussion: https://postgr.es/m/a0806273-8bbb-43b3-bbe1-c45a58f6ae21.lingce....@alibaba-inc.com Backpatch-through: 9.4 Branch ------ REL9_6_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/52684bc7d9579fefa69e09797e798dbe2b0acbd2 Modified Files -------------- src/backend/replication/syncrep.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
