Virtual-Threads on dplabs — Software Engineering & Technology Consultancy

Structured Concurrency in Java: Fixing Unstructured Concurrent Code

Mon, 28 Apr 2025 00:00:00 +0000

Java’s concurrency model has been functional for decades. ExecutorService, Future, CompletableFuture — these tools work. They also have a persistent problem: when you submit tasks to an executor, the relationship between the spawning thread and the spawned tasks is not represented in the code. Errors are easy to lose. Cancellation doesn’t propagate automatically. Resources leak when tasks outlive their intended scope.

Structured concurrency, finalized in Java 24 (JEP 505 after multiple preview rounds), fixes this. The core principle: concurrent tasks should have lifetimes that are scoped to the block of code that spawned them, just as try-with-resources scopes resource lifetimes.

Java 17 to 21: Modern Java Is a Different Language

Mon, 16 Dec 2024 00:00:00 +0000

Java 21 is the current long-term support release as of late 2024, and it represents something unusual: a Java that looks substantively different from Java 8. Not just faster or more convenient — different in how you model domains and reason about concurrency.

This article focuses on the features that arrived between Java 17 and Java 21 (covered separately) and the cohesive picture they form together.

Pattern Matching for Switch (Finalized Java 21)

Pattern matching for instanceof arrived in Java 16. Java 21 extended pattern matching to switch — and this is where the power becomes apparent.

Virtual Threads in Java 21: What They Solve and What They Don't

Mon, 04 Nov 2024 00:00:00 +0000

Virtual threads were the most anticipated Java feature in years. Project Loom’s promise was simple: write blocking code that scales like non-blocking code. Java 21 delivered them as a finalized, production-ready feature. They work. The caveats matter.

The Problem Virtual Threads Solve

Traditional Java concurrency has a fundamental constraint: platform threads are expensive. Each platform thread maps 1:1 to an OS thread. OS threads consume roughly 1MB of stack space by default and are expensive to create and context-switch.