背景
最近複習一下多線程，上面說到synchronized是將被阻塞的現場放到一個虛擬隊列（Lock-Free無鎖機制）中，而Lock是通過AQS隊列存放阻塞的線程。那synchronized裏的線程默認是怎麼競爭鎖的，Lock又是如何？
之前記錄的結論：
思路
開啓一個死循環，然後讓多個線程競爭通一把鎖，被阻塞的線程孜然就會被放到對應的阻塞隊列裏，執行時打印線程的名字，然後根據打印的結果判斷順序
先驗證synchronized的情況，創建一個runnable實現類，然後共享成員變量map
public class MyThread implements Runnable{
Map<String,String> map;
public Map<String, String> getMap() {
return map;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
@Override
public void run() {
while (true){
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (map){
System.out.println(Thread.currentThread().getName()+"拿到了鎖");
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+"結束了");
}
}
}
}
在主方法中執行
public static void main(String[] args) {
Map<String, String> map = new HashMap<>();
for (int i = 0; i < 10; i++) {
MyThread myThread = new MyThread();
myThread.setMap(map);
Thread thread = new Thread(myThread);
System.out.println(thread.getName()+"開始啓動了");
thread.start();
}
System.out.println("主線程結束了");
}
結果：線程競爭結果無順序，可以認爲當一個線程釋放鎖資源時，隊列中的其他線程都在競爭？
Thread-0開始啓動了
Thread-1開始啓動了
Thread-2開始啓動了
Thread-3開始啓動了
Thread-4開始啓動了
Thread-5開始啓動了
Thread-6開始啓動了
Thread-7開始啓動了
Thread-8開始啓動了
Thread-9開始啓動了
主線程結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-9拿到了鎖
Thread-9結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-6拿到了鎖
Thread-6結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-8拿到了鎖
Thread-8結束了
Thread-7拿到了鎖
Thread-7結束了
Thread-5拿到了鎖
Thread-5結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-5拿到了鎖
Thread-5結束了
Thread-7拿到了鎖
Thread-7結束了
Thread-8拿到了鎖
Thread-8結束了
Thread-2拿到了鎖
驗證Lock鎖的情況，通過共享一個ReentrantLock對象。
public class MyThread2 implements Runnable{
ReentrantLock reentrantLock ;
public ReentrantLock getReentrantLock() {
return reentrantLock;
}
public void setReentrantLock(ReentrantLock reentrantLock) {
this.reentrantLock = reentrantLock;
}
@Override
public void run() {
while (true){
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
reentrantLock.lock();
System.out.println(Thread.currentThread().getName()+"拿到了鎖");
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+"結束了");
reentrantLock.unlock();
}
}
}
主線程
public static void main(String[] args) {
ReentrantLock reentrantLock = new ReentrantLock(false);
for (int i = 0; i < 5; i++) {
MyThread2 myThread2 = new MyThread2();
myThread2.setReentrantLock(reentrantLock);
Thread thread = new Thread(myThread2);
System.out.println(thread.getName()+"開始啓動了");
thread.start();
}
}
結果可見，線程執行是有順序的，確實是按照順序不停更換頭結點，循環，有序拿到鎖的。
Thread-0開始啓動了
Thread-1開始啓動了
Thread-2開始啓動了
Thread-3開始啓動了
Thread-4開始啓動了
Thread-1拿到了鎖
Thread-1結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-4拿到了鎖
這裏有個疑問就是公平鎖的問題，公平鎖反應的應該是新來的線程是否應該排隊吧，已經在CLH隊列裏的線程就是按照順序執行，跟是否公平無關吧？
這裏證明一下，先讓5個線程都打印完，得以判斷出最初的隊列順序，然後再突然讓5個新的線程去競爭，看看這5個線程是否會排到後面。
public static void main(String[] args) {
ReentrantLock reentrantLock = new ReentrantLock(false);
for (int i = 0; i < 5; i++) {
MyThread2 myThread2 = new MyThread2();
myThread2.setReentrantLock(reentrantLock);
Thread thread = new Thread(myThread2);
System.out.println(thread.getName()+"開始啓動了");
thread.start();
}
try {
Thread.sleep(3500);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("開始加入額外線程");
for (int i = 0; i < 10; i++) {
MyThread2 myThread2 = new MyThread2();
myThread2.setReentrantLock(reentrantLock);
Thread thread = new Thread(myThread2);
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
thread.start();
}
System.out.println("主線程結束了");
}
設置的Lock鎖爲false，爲不公平鎖
最初順序爲3,2,4,1,0，最後結果成了3,10,5,11,2,12,6,13,4,14,7,1,8等等
根據結果可以發現確實有插隊情況出現了，確實符合理論。
Thread-0開始啓動了
Thread-1開始啓動了
Thread-2開始啓動了
Thread-3開始啓動了
Thread-4開始啓動了
Thread-3拿到了鎖
Thread-3結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-3拿到了鎖
開始加入額外線程
Thread-3結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-5拿到了鎖
Thread-5結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-6拿到了鎖
Thread-6結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-7拿到了鎖
主線程結束了
Thread-7結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-8拿到了鎖
Thread-8結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-9拿到了鎖
Thread-9結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-10拿到了鎖
Thread-10結束了
Thread-5拿到了鎖
Thread-5結束了
Thread-11拿到了鎖
Thread-11結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-12拿到了鎖
Thread-12結束了
Thread-6拿到了鎖
Thread-6結束了
Thread-13拿到了鎖
Thread-13結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-14拿到了鎖
Thread-14結束了
Thread-7拿到了鎖
Thread-7結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-8拿到了鎖
現在改成ture，也就是公平鎖，看看結果如何
結果顯示不符合預期效果，想了一下，因爲CLH他是一個帶頭結點的雙向鏈表，也就是說他的鏈表是一直在變化的，所以順序肯定不會是固定的，頭結點釋放以後，多個線程同時競爭尾部，然後再依次往前排，順序勢必會打亂。
Thread-0開始啓動了
Thread-1開始啓動了
Thread-2開始啓動了
Thread-3開始啓動了
Thread-4開始啓動了
Thread-3拿到了鎖
Thread-3結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-3拿到了鎖
開始加入額外線程
Thread-3結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-5拿到了鎖
Thread-5結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-6拿到了鎖
Thread-6結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-7拿到了鎖
主線程結束了
Thread-7結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-8拿到了鎖
Thread-8結束了
Thread-0拿到了鎖
Thread-0結束了
Thread-9拿到了鎖
Thread-9結束了
Thread-3拿到了鎖
Thread-3結束了
Thread-10拿到了鎖
Thread-10結束了
Thread-5拿到了鎖
Thread-5結束了
Thread-11拿到了鎖
Thread-11結束了
Thread-2拿到了鎖
Thread-2結束了
Thread-12拿到了鎖
Thread-12結束了
Thread-6拿到了鎖
Thread-6結束了
Thread-13拿到了鎖
Thread-13結束了
Thread-4拿到了鎖
Thread-4結束了
Thread-14拿到了鎖
Thread-14結束了
Thread-7拿到了鎖
Thread-7結束了
Thread-1拿到了鎖
Thread-1結束了
Thread-8拿到了鎖
進一步改造一下ReentrantLock ，打印出他的隊列內的元素。
public class ReentrantLockMine extends ReentrantLock {
public ReentrantLockMine(boolean fair) {
super(fair);
}
@Override
protected Collection<Thread> getQueuedThreads() { //獲取同步隊列中的線程
List<Thread> arrayList = new ArrayList<Thread>(super.getQueuedThreads());
Collections.reverse(arrayList);
return arrayList;
}
}
這邊也是改一下內部的成員變量
public class MyThread2 implements Runnable{
ReentrantLockMine reentrantLock ;
public ReentrantLock getReentrantLock() {
return reentrantLock;
}
public void setReentrantLock(ReentrantLockMine reentrantLock) {
this.reentrantLock = reentrantLock;
}
@Override
public void run() {
while (true){
reentrantLock.lock();
System.out.println(Thread.currentThread().getName()+"拿到了鎖,當前隊列："+((ReentrantLockMine)reentrantLock).getQueuedThreads());
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+"結束了");
reentrantLock.unlock();
}
}
}
測試方法
public static void main(String[] args) {
ReentrantLockMine reentrantLock = new ReentrantLockMine(false);
for (int i = 0; i < 5; i++) {
MyThread2 myThread2 = new MyThread2();
myThread2.setReentrantLock(reentrantLock);
Thread thread = new Thread(myThread2);
System.out.println(thread.getName()+"開始啓動了");
thread.start();
}
try {
Thread.sleep(1500);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("開始加入額外線程");
for (int i = 0; i < 10; i++) {
MyThread2 myThread2 = new MyThread2();
myThread2.setReentrantLock(reentrantLock);
Thread thread = new Thread(myThread2);
thread.start();
}
System.out.println("主線程結束了");
}
非公平結果：
可以發現，之後加入的線程全部按照順序排在了後面，0號線程拿到線程後又插隊獲取到鎖，繼續執行，其他線程拿不到鎖。
Thread-0開始啓動了
Thread-1開始啓動了
Thread-2開始啓動了
Thread-3開始啓動了
Thread-4開始啓動了
Thread-0拿到了鎖,當前隊列：[]
Thread-0結束了
Thread-0拿到了鎖,當前隊列：[Thread[Thread-1,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main]]
Thread-0結束了
Thread-0拿到了鎖,當前隊列：[Thread[Thread-1,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main]]
開始加入額外線程
主線程結束了
Thread-0結束了
Thread-0拿到了鎖,當前隊列：[Thread[Thread-1,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-12,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-9,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main]]
Thread-0結束了
Thread-0拿到了鎖,當前隊列：[Thread[Thread-1,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-12,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-9,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main]]
Thread-0結束了
Thread-0拿到了鎖,當前隊列：[Thread[Thread-1,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-12,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-9,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main]]
公平鎖結果：
可以發現全部按照隊列順序去執行了，不存在某個線程一直獲取資源，符合預期效果。
Thread-0開始啓動了
Thread-1開始啓動了
Thread-2開始啓動了
Thread-3開始啓動了
Thread-4開始啓動了
Thread-0拿到了鎖,當前隊列：[]
Thread-0結束了
Thread-1拿到了鎖,當前隊列：[Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main]]
Thread-1結束了
Thread-4拿到了鎖,當前隊列：[Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main]]
開始加入額外線程
主線程結束了
Thread-4結束了
Thread-2拿到了鎖,當前隊列：[Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main]]
Thread-2結束了
Thread-3拿到了鎖,當前隊列：[Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main]]
Thread-3結束了
Thread-0拿到了鎖,當前隊列：[Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main]]
Thread-0結束了
Thread-1拿到了鎖,當前隊列：[Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main]]
Thread-1結束了
Thread-5拿到了鎖,當前隊列：[Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main]]
Thread-5結束了
Thread-7拿到了鎖,當前隊列：[Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main]]
Thread-7結束了
Thread-6拿到了鎖,當前隊列：[Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main]]
Thread-6結束了
Thread-8拿到了鎖,當前隊列：[Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main]]
Thread-8結束了
Thread-9拿到了鎖,當前隊列：[Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main]]
Thread-9結束了
Thread-10拿到了鎖,當前隊列：[Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main]]
Thread-10結束了
Thread-11拿到了鎖,當前隊列：[Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main]]
Thread-11結束了
Thread-12拿到了鎖,當前隊列：[Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main]]
Thread-12結束了
Thread-13拿到了鎖,當前隊列：[Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main]]
Thread-13結束了
Thread-14拿到了鎖,當前隊列：[Thread[Thread-4,5,main], Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main]]
Thread-14結束了
Thread-4拿到了鎖,當前隊列：[Thread[Thread-2,5,main], Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main]]
Thread-4結束了
Thread-2拿到了鎖,當前隊列：[Thread[Thread-3,5,main], Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main]]
Thread-2結束了
Thread-3拿到了鎖,當前隊列：[Thread[Thread-0,5,main], Thread[Thread-1,5,main], Thread[Thread-5,5,main], Thread[Thread-7,5,main], Thread[Thread-6,5,main], Thread[Thread-8,5,main], Thread[Thread-9,5,main], Thread[Thread-10,5,main], Thread[Thread-11,5,main], Thread[Thread-12,5,main], Thread[Thread-13,5,main], Thread[Thread-14,5,main], Thread[Thread-4,5,main], Thread[Thread-2,5,main]]
結論
synchronized的隊列似乎並不有序，根據Lock-Free的解釋，它屬於一個虛擬的隊列，隊列裏的各個數據都在競爭鎖。
Lock嚴格按照隊列順序執行，若非公平鎖狀態則可能被非隊列中的現場插隊執行，公平鎖狀態下按照隊列順序，只有頭結點纔回去嘗試獲取鎖，和synchronized都在競爭鎖情況相比可能更節省資源？但是同一時刻多線程入隊的順序是不確定的（霧）。