If you want to get better at sports, you have to train. The same applies to improving your observability skills. Application Observability Code Challenges as puzzlers are here to train you.
For example virtual threads can be very useful, but if there are problems with virtual threads, do you know how to spot them?

With these challenges, you can work through a prepared challenge with a prepared setup. The code contains some issues that you need to identify. Observability tools such as Grafana are already in place (or you can use your own). By making changes to the code, run the test and you can view the results in raw metrics, logs, traces, and prepared dashboards.
These exercises help you practice using observability tools such as Grafana.

Sometimes problems are not that obvious, even if you have a stacktrace. Adding more information to your traces, logs and metrics will give you more insights, I will tell you how to do that.

Alerts from production, help me!! Stay calm — I know what to do!
If you are trained, you know how to use the observability tools to identify problems, you will feel comfortable using them. It is important to be prepared for the real situation in order to handle an incident adequately.

I will explain what these code challenges look like and how to run them and I will give a sneak peak, but I will not demonstrate the full challenges — that's your job!