SQS maximum inflight message count is lower than documentation says

Question

According to the SQS documentation , the maximum number of inflight messages is set to 120,000 for standard queues. However, sometimes I see my queues maxing out at lower numbers, such as here:

Does anyone know why this might be the case? I have code that dynamically changes the number of SQS listeners depending on the number of messages in the queue, but I don't want to do anything if I've hit the maximum. My problem is now that the max limit doesn't seem to be consistent. Some queues go to 120K, but this one is stuck at 100K instead, and as far as I can tell there is no setting that allows me to set this limit.

Answer 1

approximateNumberOfMessagesNotVisible indicates the number of messages in-flight, as you are rightly said. It depends on how many consumers you have, and what is througput of each consumer.

If the actual number is caping at 100k, then your consumers are swamped and have no more receiving capacity.

Anyways, it's better if you provide more info on the use-case as 100k in-flight messages look out of ordinary and you may be not using correct solution for your problem.