-When you use the [peek lock](message-transfers-locks-settlement.md#peeklock) receive mode, messages fetched into the prefetch buffer are acquired into the buffer in a locked state. They have the timeout clock for the lock ticking. If the prefetch buffer is large, and processing takes so long that message locks expire while staying in the prefetch buffer or even while the application is processing the message, there might be some confusing events for the application to handle. The application might acquire a message with an expired or imminently expiring lock. If so, the application might process the message, but then find that it can't complete the message because of a lock expiration. The application can check the `LockedUntilUtc` property (which is subject to clock skew between the broker and local machine clock). If the message lock has expired, the application must ignore the message, and shouldn't make any API call on the message. If the message isn't expired but expiration is imminent, the lock can be renewed and extended by another default lock period. If the lock silently expires in the prefetch buffer, the message is treated as abandoned and is again made available for retrieval from the queue. It might cause the message to be fetched into the prefetch buffer and placed at the end. If the prefetch buffer can't usually be worked through during the message expiration, messages are repeatedly prefetched but never effectively delivered in a usable (validly locked) state, and are eventually moved to the dead-letter queue once the maximum delivery count is exceeded.
0 commit comments