Loading messages between modules

Load testing involves firing many messages at an application’s external interfaces, but internal messaging will also have high usage when the system is busy. Another class of issues arises from overloading those communication flows.

Do your internal messages have suitable queues, retries, back-offs, and failure modes? This is another class of issue best probed with load testing to ensure there are no hidden bottlenecks within your system.

This section is hard to describe because both the causes and effects are indirect and can be difficult to trigger with system testing. You will have to check with the development team which operations will cause the highest rate of internal messaging within your system; this is an area where you need white-box insights. It won’t be clear what symptoms internal message failures might produce. Operations could time out or fail; the system might be left in an inconsistent state, with some processes...