How to prove your Ratpack app is non-blocking.
Using the Ratpack framework can be tricky. It's easy to get something working but it's harder to ensure that your code is non-blocking. This post will detail how to prove your code is non-blocking with automated tests. Background - What's the problem? In order to realise the performance benefits of the Ratpack framework you have to ensure that your code is non-blocking. This means ensuring that your Java Threads are always busy and not waiting for I/O (i.e. non-blocking). As soon as your thread kicks off an I/O task (e.g. sending a http request or making a DB call), it should be able to switch to another task. Once the I/O eventually completes an event is fired which informs that the next step in the code can be performed, typically doing something with the result of the I/O task. This means that a huge number of tasks which are I/O bound (i.e. spend a significant amount of time waiting for I/O)...