Can you explain what virtual threads are and how they work?

Virtual Threads are a new feature in Java introduced in version 19 as part of the Loom project. They are lightweight threads managed not directly by the operating system but by the Java Virtual Machine (JVM).

Unlike traditional OS threads, virtual threads have very low overhead for creation and switching, allowing the creation of thousands or even millions of concurrent tasks without significant resource consumption.

How it works:

• Virtual threads are implemented on top of an OS thread pool, but appear as regular threads to the developer.
• The JVM manages scheduling and switching of virtual threads independently, relieving developers from these complexities.
• They are especially useful for tasks with many blocking I/O operations, such as network requests.

Example of creating a virtual thread:

Thread.startVirtualThread(() -> {
    System.out.println("Virtual thread is running");
});

Thus, virtual threads simplify writing scalable and efficient multithreaded code.