A custom synchronizer extends AQS and overrides tryAcquire/tryRelease but stores its lock count in an extra instance field rather than calling setState/getState. Acquire and release appear to work in single-threaded tests but corrupt under contention. What is the core internals reason?

class BadLock extends AbstractQueuedSynchronizer { private int count; // NOT the AQS state protected boolean tryAcquire(int arg) { if (count == 0) { count = 1; setExclusiveOwnerThread(Thread.currentThread()); return true; } return false; } protected boolean tryRelease(int arg) { count = 0; return true; } }