Amazon SQS maximum in flight messages
So I tried it myself and came to the following conclusion:
- FIFO queues can hold an unlimited amount of messages
- After peeking 20k messages (that are now considered "in flight"), you don't get any more messages trying to peek other available messages
- After the receive handle of a in flight message expires, it will be deducted from the "in flight" quota and is considered "available" again
- The service peeking messages, when the 20k quota is reached, does not get any error message but instead receives an empty message list.