Java死锁怎么分析 java死锁分析 _小知识

所谓死锁是指两个或两个以上的线程在执行过程中，因争夺资源而造成的一种互相等待的现象，若无外力作用，它们都将无法推进下去。

以下分别使用 lock 与 synchronized 来产生死锁，再定位与分析
一、制造死锁synchronized 版本：
public class DeadLockDemo {public static void main(String[] args) {Object lock1 = new Object();Object lock2 = new Object();new Thread(() -> {synchronized (lock1) {// 线程 t1 持有 lock1锁，还要获取 lock2 锁（但 lock2 t2线程占有）System.out.println(Thread.currentThread().getName() + " get lock1 ");try {TimeUnit.MILLISECONDS.sleep(10);} catch (InterruptedException e) {e.printStackTrace();}synchronized (lock2) {}}}, "t1").start();new Thread(() -> {synchronized (lock2) {// 线程 t2 持有 lock2锁，还要获取 lock1 锁（但 lock1被 t1线程占有）System.out.println(Thread.currentThread().getName() + " get lock2 ");synchronized (lock1) {}}}, "t2").start();}}Lock版本：
public class DeadLockDemo {public static void main(String[] args) {Lock lock1 = new ReentrantLock();Lock lock2 = new ReentrantLock();// 线程 t1 持有 lock1 ，等到 lock2 锁的到来（但 lock2被 t2线程占用）new Thread(() -> {try {lock1.lock();System.out.println(Thread.currentThread().getName() + " get lock1 ");TimeUnit.MILLISECONDS.sleep(100);// 设置延时lock2.lock();System.out.println(Thread.currentThread().getName() + " get lock2 ");} catch (InterruptedException e) {e.printStackTrace();} finally { lock1.unlock();}}, "t1").start();// 线程 t2 持有 lock2 ，等到 lock1 锁的到来（但 lock1被 t1线程占用）new Thread(() -> {try {lock2.lock();System.out.println(Thread.currentThread().getName() + " get lock1 ");lock1.lock();System.out.println(Thread.currentThread().getName() + " get lock2 ");} finally { lock2.unlock();}}, "t2").start();}}二、死锁现象