死锁：两个或两个以上的线程在执行的过程中，因为竞争资源或者彼此期待彼此而造成彼此期待彼此，线程不再往下执行。
依据以上示例图构建连个死锁程序
（1）DeadLock
package com.high.concurrency.currency02.eat;public class DeadLock extends Thread { private String first; private String second; public DeadLock(String name, String first, String second) { super(name); this.first = first; this.second = second; } @Override public void run() { synchronized (first) { try { System.out.println(this.getName() + " ...synchronized:===> 【first】" + first); Thread.sleep(1000L); synchronized (second) { System.out.println(this.getName() + " ...synchronized:===>【second】 " + second); } } catch (InterruptedException e) {} } } public static void main(String[] args) throws InterruptedException { String lockA = "lockA"; String lockB = "lockB"; DeadLock t1 = new DeadLock("t1", lockA, lockB); DeadLock t2 = new DeadLock("t2", lockB, lockA); t1.start(); t2.start(); t1.join(); t2.join(); }}（2）PhilosopherEatingpackage com.high.concurrency.currency02.eat;public class PhilosopherEating extends Thread { protected Object tool; static Object fork1 = new Object(); static Object fork2 = new Object(); public PhilosopherEating(Object obj) { this.tool = obj; if(tool == fork1) { this.setName("哲学家A"); } if (tool == fork2) { this.setName("哲学家B"); } } @Override public void run() { if(tool == fork1) { synchronized (fork1) { try { Thread.sleep(500); } catch (Exception e) { e.printStackTrace(); } synchronized (fork2) { System.out.println("哲学家A开始吃饭了"); } } } if (tool == fork2) { synchronized (fork2) { try { Thread.sleep(500); } catch (InterruptedException e) { e.printStackTrace(); } synchronized (fork1) { System.out.println("哲学家B开始吃饭了"); } } } } public static void main(String[] args) throws InterruptedException { PhilosopherEating philosonpherA = new PhilosopherEating(fork1); PhilosopherEating philosonpherB = new PhilosopherEating(fork2); philosonpherA.start(); philosonpherB.start(); Thread.sleep(1000); }}上述程序都体现一个特点： 存在两个线程，呈现我应用这以后的资源， 申请对方正在应用的资源，而对方尚未开释该资源导致线程阻塞。
查找线程死锁的方法：jps + jstack
首先在终端输出jps，查找到对应的死锁过程号：
获取到对应的死锁过程，输出jstack + 过程号， 找到对应的报错信息，依据报错信息进行下一步的批改