死锁的演示

死锁

当业务比较复杂时，多线程应用里有可能会发生死锁

演示死锁

1. 线程一占有对象一，试图占有对象二
2. 线程二占有对象二，试图占有对象一
3. 线程一等待线程二释放线程二
4. 线程二等待线程一释放线程一

练习

package multiThread2;

public class main1 {
   public static void main(String[] args) {
       Animal a1 = new Animal();
       Animal a2 = new Animal();
       Animal a3 = new Animal();
       Thread t1 = new Thread(new Runnable() {
           @Override
           public void run() {
               synchronized (a1){
                   System.out.println("a1在做饭");
                   try {
                       Thread.sleep(1000);
                   }catch (Exception e){
                       throw new RuntimeException(e);
                   }
                   System.out.println("a1试图干饭");
                   System.out.println("a1等待着");
                   synchronized (a2){
                       System.out.println("a1 doing");
                   }
               }
           }
       });
       t1.start();
       Thread t2 = new Thread(new Runnable() {
           @Override
           public void run() {
               synchronized (a2){
                   System.out.println("a2在做饭");
                   try {
                       Thread.sleep(1000);
                   }catch (Exception e) {
                       throw new RuntimeException(e);
                   }
                   System.out.println("a2试图干饭");
                   System.out.println("a2等待着");
                   synchronized (a3){
                       System.out.println("a2 doing");
                   }
               }
           }
       });
       t2.start();
       Thread t3 = new Thread(new Runnable() {
           @Override
           public void run() {
               synchronized (a3){
                   System.out.println("a3在做饭");
               }
               try {
                   Thread.sleep(1000);
               }catch (Exception e){
                   throw new RuntimeException(e);
               }
               System.out.println("a3试图干饭");
               System.out.println("a3等待着");
               synchronized (a1){
                   System.out.println("a3 doing");
               }
           }
       });
       t3.start();
   }
}