The next phase of Project Loom and Virtual Threads by Alan Bateman

Virtual threads are lightweight threads that enable high scalability without complex async programming models - they are “threads without the baggage”

Virtual threads are not pooled and should not be - they are created per task, execute it, and terminate. They are very cheap to create

The synchronized keyword works with virtual threads, but may cause “pinning” which impacts scalability. JEP 491 will address this in JDK 24

Structured concurrency (JEP 428) provides better task management than Futures, ensuring child tasks complete before parent tasks continue

New diagnostic capabilities in JDK 24 improve troubleshooting:

• Enhanced thread dumps showing virtual thread details
• JFR events for pinning diagnostics
• Heap dumps now include unmounted virtual thread stacks

Virtual threads don’t make code run faster - they provide scalability benefits by allowing more concurrent operations with simple blocking code

The focus is on enabling simple synchronous blocking code rather than complex async programming models

Virtual threads are mounted on carrier threads (platform threads) and unmount when blocking to free the carrier for other work

Structured concurrency preserves parent-child relationships between tasks and handles cancellation/cleanup automatically

Common misconceptions:

• Virtual threads are not faster than platform threads
• No need to replace all synchronized code
• Not meant for thread pooling