1. ThreadLocal ：
ThreadLocal myNode = new ThreadLocal() {
protected QNode initialValue() {
return new QNode();
} ThreadLocal<T> 能够访问 Thread 的
};
threadLocalMap
key 是 threadLocal 对象，
value 是具体使用的 <T> 值
public T get() {
Thread t = Thread.currentThread();
ThreadLocalMap map = getMap(t);
if (map != null) {
ThreadLocalMap.Entry e = map.getEntry(this);
if (e != null)
return (T)e.value;
}
return setInitialValue(); }

2. myNode
myNode(ThreadLocal )
CLHLock myPred
Thread1
tail
myPred (ThreadLocal )
Thread 2 tail (Node)
CLHLock ：
Thread N public void lock() {
QNode node = myNode.get();
node.locked = true;
QNode pred = tail.getAndSet(node);
Thread ： myPred.set(pred);
CLHLock.lock() while (pred.locked) {
doSomeThing(); }
CLHLock.unlock(); }

3. CLHLock: 对象 ThreadLocal
myNode
myPred ：对象域
node ：局部变量
CLHLock myPred
ThreadLocal
myNodeKey ：
myPred,myNode,tail
ThreadLocal myNode
tail
as Key
node
QNode QNode
locked=true locked=false
myNodeKey
Thread1
Thread1 ： lock()
QNode node = myNode.get();
node.locked = true;

4. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node pred
QNode QNode
locked=true locked=fasle
myNodeKey
myPredKey
Thread1
Thread1 ： lock()
QNode pred = tail.getAndSet(node);
myPred.set(pred);
while (pred.locked) {
}

5. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node
QNode QNode QNode
locked=true locked=true locked=fasle
myNodeKey myNodeKey
myPredKey
Thread2 Thread1
Thread2 ： lock()
QNode node = myNode.get(); Thread1 ：
node.locked = true; dosomeThing(){
……
}

6. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node pred
QNode QNode QNode
locked=true locked=true locked=fasle
myNodeKey myNodeKey
myPredKey
myPredKey
Thread2 Thread1
Thread2 ： lock() Thread1 ：
QNode pred = tail.getAndSet(node); dosomeThing(){
myPred.set(pred);
while (pred.locked) {
……
LockSupport.park(this); //block }
}

7. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node node pred
QNode QNode QNode
locked=true locked=false locked=fasle
myNodeKey
myNodeKey
myPredKey
myPredKey
Thread2 Thread1
Thread2 ： lock() Thread1 ： unlock ()
QNode pred = tail.getAndSet(node); QNode node = myNode.get();
myPred.set(pred); node.locked = false;
while (pred.locked) {
LockSupport.park(this); //block myNode.set(myPred.get());
}

8. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
QNode QNode QNode
locked=true locked=false locked=fasle
myNodeKey
myNodeKey
myPredKey
myPredKey
Thread2 Thread1
Thread2 ： Dosomthing(){
}

9. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node
QNode QNode QNode
locked=false locked=false locked=fasle
myNodeKey
myNodeKey
myPredKey
myPredKey
Thread2 Thread1
Thread2 ： unlock();
QNode node = myNode.get();
node.locked = false;
myNode.set(myPred.get());

10. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node
QNode QNode QNode
locked=false locked=false locked=true
myNodeKey
myNodeKey
myPredKey
myPredKey
Thread2 Thread1
Thread1 ： lock()
QNode node = myNode.get();
node.locked = true;

11. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
pred node
QNode QNode QNode
locked=false locked=false locked=true
myPredKey myNodeKey
myNodeKey
myPredKey
Thread2 Thread1
Thread1 ： lock()
QNode pred = tail.getAndSet(node);
myPred.set(pred);
while (pred.locked) {
}

12. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node
QNode QNode QNode
locked=false locked=false locked=true
myPredKey myNodeKey
myNodeKey
myPredKey
Thread2 Thread1
Thread1 ： lock() 后再次调用 lock()
QNode node = myNode.get();
node.locked = true;

13. ThreadLocal
myNode
CLHLock myPred
ThreadLocal
myPred,myNode,tail
tail
node pred
QNode QNode QNode
locked=false locked=false locked=true
myNodeKey
myNodeKey
myPredKey
myPredKey
Thread2 Thread1
Thread1 ： lock()
QNode pred = tail.getAndSet(node);
myPred.set(pred);
while (pred.locked) { // 永远 true 不可重入锁
}