Flight Recorder is a low overhead profiler and diagnostics events recorder for the Hotspot JVM. Java Mission Control is a software to visualize these events. It has been included for years in the Oracle JDK but used to be a commercial feature. To use it you needed to add -XX:+UnlockCommercialFeatures -XX:+FlightRecorder flags and you were not allowed to use it in production unless you paid a license.

Yesterday I had an app with an embedded Jetty Server which didn’t shut down properly. The main thread exited and the app had called .stop() on the Jetty server. However, the app kept running.

Multiple times I needed to create HTTPS certificates programmatically. For example to create test certificates for HTTPS in development without complicated setup. There is surprisingly little information out there about how to create certificates programmatically in Java. Most guides OpenSSL or another command-line tool. I wanted to avoid to run an external program but wanted to do it programmatically.

TLDR: I recommend using Bouncy Castle instead of this method. I used this method in the past but I’m using Bouncy Castle now to support Java 11+.

A few months backs I implemented logic which needs to lookup entries in a big existing table, but the lookup wasn’t easy indexable. Here’s a guide on one approach you can take. I’m using SQL Server for this example. Let’s assume we have a table with guests, something like this