Backend & systems·Queues, streams and delivery semantics
the message is hidden from other workers while you process it, and reappears if you do not finish in time.
Visibility timeout
Also calledack deadline, lease timeout
The window during which a claimed message is invisible to other consumers, after which it is redelivered. It is the mechanism that makes crash recovery automatic. Set it shorter than your actual processing time and you get concurrent duplicate processing of every slow message, which looks exactly like a race condition in your own code.