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. I’ve written about Scoped Values before, but so far, only Virtual Threads (JEP 444) has been released out of preview. But today, we will look at the “glue” that can hold it all together: Structured Concurrency (JEP 453).

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. Let’s take a look at some of the “other” changes that Java 21 gave us!

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. As in many of my other articles, let’s look first at the status quo before a new feature to understand betters what problem it tries to solve and what the benefits are. Platform Threads Before the introduction of Virtual Threads, the Threads we’re used to, java.

Shell redirection can be confusing. I’ve always wondered what 2>&1 means and why it’s needed, but as many others, I just copy/pasted things from the internet into my terminal and hoped for the best. What could possibly go wrong? But no more! It’s finally time to look behind the curtain and decipher and understand what’s actually happening.

Around 6 years ago, I wrote about using Java for shell scripts. It was a hacky and fragile way to convert some Java code into a shebanged file containing the content of a Jar file. However, Java evolved quite a bit since that article, so it’s time to look at it again.