Platform threads map 1:1 to OS threads. When a thread blocks on I/O, the OS scheduler parks a core. With Virtual Threads (Java 21+), the JVM manages millions of lightweight threads. Blocking on I/O yields the virtual thread without yielding the OS thread.
Subtitle: A Professional Developer’s Guide to JVM Deep Dives, Performance Tuning, and Enterprise Frameworks PDF Description (Back Cover / Blurb) "You’ve mastered the syntax. You’ve built your first Spring Boot API. Now it’s time to stop writing code that just ‘works’—and start writing code that scales, survives, and performs." advanced java pdf