PeekLock 模式下的 Peek() 方法是否锁定服务总线消息？

Question

I know we can use Receive() method on PeekLock mode, to Lock the message, process it and finally Complete() it. But, how does Peek() method work on PeekLock mode? Does it lock the message?

var client = messagingFactory.CreateQueueClient("entity", ReceiveMode.PeekLock);
BrokeredMessage = client.Peek();

Also, as a second question, I know we can repeatedly call the Peek() to peek all the Active end messages. But, can Peek() method be used repeatedly to Peek all the dead lettered messages?

Answer 1

But, how does Peek() method work on PeekLock mode? Does it lock the message?

No, Peek() does not lock the message regardless of the mode. Mode is applicable to Receive() only. Not only that Peek() can even return message which are locked by another receiver.

But, can Peek() method be used repeatedly to Peek all the dead lettered messages?

Yes, deadlettered messages resides in another special queue. You can Peek() from it just like a normal queue.

Also to improve throughput, you can use PeekBatch instead of Peek .

In summary, Peek is the API for message browsing/diagnostics purpose. You may want to give the official documentation a quick read.

Note: The peek operation on a non-partitioned entity always returns the oldest message, but not on a partitioned entity. Instead, it returns the oldest message in one of the partitions whose message broker responded first. There is no guarantee that the returned message is the oldest one across all partitions.

Answer 2

Peek does not lock the message. In fact, Peek doesn't even know any detail about the lock. This is what the docs say:

Peek also returns messages that were locked and are currently being processed by other receivers. However, because Peek returns a disconnected snapshot, the lock state of a message can't be observed on peeked messages.

You can check this by accessing the messages's lock property, such as LockedUntilUtc . This will return you an exception InvalidOperationException .

The answer for your second question is simply "Yes". You can browse messages both active messages and dead-letters.