Virtual threads: synchronized pins the carrier, ReentrantLock does not

A virtual thread that blocks inside a synchronized block holds its carrier platform thread hostage. The same code under a ReentrantLock unmounts cleanly. With an uncontended lock per task, the only difference left is pinning - and it serialises everything.

Full code & output

This topic is available to PRO members.

Sign in Create a free account

Run this yourself in the Online Java Compiler, spin up a live REST API in the API Sandbox, or practise with Java interview questions.

Published 2026-08-25