diff options
| -rw-r--r-- | src/backend/storage/ipc/shm_mq.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/src/backend/storage/ipc/shm_mq.c b/src/backend/storage/ipc/shm_mq.c index 40df8e1251e..3faace249ff 100644 --- a/src/backend/storage/ipc/shm_mq.c +++ b/src/backend/storage/ipc/shm_mq.c @@ -1058,7 +1058,19 @@ shm_mq_receive_bytes(shm_mq_handle *mqh, Size bytes_needed, bool nowait, * detached. */ if (mq->mq_detached) + { + /* + * If the writer advanced mq_bytes_written and then set + * mq_detached, we might not have read the final value of + * mq_bytes_written above. Insert a read barrier and then check + * again if mq_bytes_written has advanced. + */ + pg_read_barrier(); + if (written != pg_atomic_read_u64(&mq->mq_bytes_written)) + continue; + return SHM_MQ_DETACHED; + } /* * We didn't get enough data to satisfy the request, so mark any data |