Long-term latency test with MIMIC MQTT Simulator

If your large-scale IoT application has latency requirements, you want
to do long-term testing to ensure your environment satisfies those
requirements.

We ran the end-to-end latency test as shown in this published video
with MIMIC MQTT Simulator against a third-party MQTT broker setup
overnight, and graphed the latency reported by our subscriber client
action script with Grafana.

The setup simulates 3000 MQTT clients, of which one is the subscriber
that measures round-trip delay of published messages to unique topics.
This tests a common fan-out scenario.

We did not expect to find anything interesting. The attached picture
shows a good steady state, with average and max latency times below
and around 500 msec (respectively) ... most of the time.

But, there are 2 instances where max latency times are above 1 second.

If your IoT application requirement is latency times below 1 second,
you'd be worried, and would need to start investigating. Without this
test you would never know about any long-term problems in your setup.