Thread-per-request programming limits application scalability, leading developers to adopt thread sharing and asynchronous programming to better utilize hardware, though this introduces additional complexity. Creating reactive pipelines, debugging them, and visualizing their execution can be complicated tasks, compounded by the complexities that arise when exceptions occur.
Java Virtual Threads enable applications to scale while preserving the thread-per-request style programming. Just as operating systems create the illusion of abundant memory by mapping a large virtual address space to limited physical RAM, a Java runtime can create the illusion of many threads by mapping numerous virtual threads to a few OS threads.
Let's explore Java virtual threads, including how they work under the hood, their use cases, and the APIs introduced by Project Loom. We'll also compare traditional threads with virtual threads through a simple programming example to see their benefits in action.