Project Loom, with its aim to deliver “easy-to-use, high-throughput, lightweight concurrency”, will most likely change how we approach concurrency in the future. Today, we will look at the “glue” that can hold it all together: Structured Concurrency.

Besides the “big” features that often aggregate under well-known project names, like “Amber”, “Loom”, or “Panama”, there are many little things in every release that are easy to miss. These API and tool improvements might not be as visible as other features, as they’re not represented by a JEP. That doesn’t mean we don’t need to know about them.

One of the most significant features of Java 21 is Virtual Threads (JEP 444). These lightweight threads reduce the effort needed for writing, maintaining, and observing high-throughput concurrent applications.

A new garbage collector was introduced in Java 11, a low latency/high scalability GC called ZGC. And now, with Java 21, it has evolved into a generational GChugo .

Pattern matching is a declarative and composable approach for more powerful and expressive code. Java 16 added pattern matching for the instanceof operator, and we looked at pattern matching for switch before. Let’s look at another new kind of pattern matching: Record Patterns.

Even though Java is one of the most backward-compatible languages and environments I’ve ever worked with, there’s always the possibility of feature deprecations and even removals.