P in temPel

The solution is profiling

Profiling helps us to gather information about our application that we usually wouldn’t see. It provides us with data on the duration of function calls, what is pushed to the stack, what is on the heap, etc. Numerous implementations exist, as it is a concept older than most programming languages. As profiling is tedious, many users opt to implement it when needed. This is the equivalent of making a backup when you need it.

Meet continuous profiling 

Continuous profiling provides us with the power of context and historical data. This lets us see which features are causing slowdowns and provide alerts before our container runs out of memory. Overall, more data means more correlations and – ultimately – better outcomes. We are coming to our Spaceship engine, the JVM.

Since Java 11, there is a feature in the Java Virtual Machine to record what is happening, called ✨ JFR ✨.  The origins of the Java Flight Recorder can be traced back to Oracle JDK 8, which was made available as open-source by Oracle in 2018. JFR mitigates the black box effect you usually get when running applications. Nonetheless, utilizing them alone can prove to be challenging.

On the other hand, Cryostat is a tool to start a

and stop these recordings. If JFRs are like a video camera, Cryostat would be the remote for that camera. It can control which application for which period should be recorded. JFRs need to be manually started and saved to a specific location. Cryostat does that via the JMX (Java Management Extension) port to the JVM. It simply connects to the „spaceship“ and says, please record a flight recording. When done – in continuous mode after approximately 2 hours – it gets and saves the recording. Therefore, you can look it up anytime. Even if your pod fulfills the inevitable promise of Kubernetes: that it will eventually die.

 Cryostat provides a Grafana data source for simple analysis where you can look up the heap size, thread use, etc.

While it is sometimes useful, the real advantages come with the Java Mission Control (that’s why it’s a space analogy, duuhhh)

With your Mission Control Center, you can explore the depths of your spaceship. This tool enables you to see the various classes in memory and identify where the CPU is being utilized the most. By doing so, you can pinpoint and address any performance issues.