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_5_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/0927d0c25c567564f1ce24ab9d8d6f1c5d83f1f0 Modified Files -------------- src/backend/replication/syncrep.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
