Understanding Java Virtual Threads: Lightweight Concurrency in Modern Java
Java 21 introduced one of the most significant changes to the platform's concurrency model in years: virtual threads, delivered as part of Project Loom (JEP 444). If you've ever struggled with thread pool tuning or hit scalability walls with blocking I/O, virtual threads are worth understanding.
The Problem with Platform Threads
Traditional Java threads (now called platform threads) are thin wrappers around operating system threads. They are expensive:
Each thread consumes around 1 MB of stack memory by default.
