Fig. 7.33 shows an alternative implementation of CLHLock in which a thread reuses its own node instead of its predecessor node. Explain how this implementation can go wrong.

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2 1 public class BadCLH Lock implements Lock { // most recent lock holder AtomicReference tail; // thread-local variable ThreadLocal myNode; public void lock () { Qnode qnode myNode.get(); 3 4 5 6 7 8 9 10 11 12 13 14. 15 16 17 qnode.locked= true; // I'm not done // Make me the new tail, and find my predecessor Qnode pred = tail.getAndSet (qnode); // spin while predecessor holds lock while (pred.locked) {} } public void unlock() { // reuse my node next time myNode.get ().locked = false; } static class Qnode { // Queue node inner class public boolean locked = false; 18 19 20 21 } Figure 7.33 An incorrect attempt to implement a CLHLock. } 2 1 public class BadCLH Lock implements Lock { // most recent lock holder AtomicReference tail; // thread-local variable ThreadLocal myNode; public void lock () { Qnode qnode myNode.get(); 3 4 5 6 7 8 9 10 11 12 13 14. 15 16 17 qnode.locked= true; // I'm not done // Make me the new tail, and find my predecessor Qnode pred = tail.getAndSet (qnode); // spin while predecessor holds lock while (pred.locked) {} } public void unlock() { // reuse my node next time myNode.get ().locked = false; } static class Qnode { // Queue node inner class public boolean locked = false; 18 19 20 21 } Figure 7.33 An incorrect attempt to implement a CLHLock. }