Part 2 of Java Thread Programming describes techniques for working with Java threads. It offers the best thread-pooling coverage and a great chapter on breaking out of blocked I/O.

Structured concurrency is a match for virtual threads, which is a lightweight implementation of threads provided by the JDK. A preview of virtual threads is planned for Java 19 this September.

Virtual threads, revealed in Java's Project Loom and generally available with the Java 21 LTS, promise unparalleled scalability, simplified asynchronous coding and more efficient resource utilization.

JDK 21's virtual threads are a major leap forward for Java's concurrency model. Previously, Java relied on OS threads, which were resource-heavy, limiting how many threads could run concurrently.