<转载>--java多线程死锁例子 TestDeadLock.java

sulifeng

多线程的东西看了有两三遍了,但是直到数据库这门专业课都学完了,印象还是不很深刻,在备考的时候死记硬背了一些事务啦、死锁啦、隔离级别之类的概念,跟多线程有点共通之处.
  
  最近在看马士兵的视频教程,加深理解.

  貌似java的多线程没有判断死锁的机制,数据库里面是会判断是否发生死锁的.下面这个例子里却是无止境地等待对方释放资源.

public class TestDeadLock implements Runnable {public int flag = 1;static Object o1 = new Object();static Object o2 = new Object();public static void main(String[] args) {TestDeadLock t1 = new TestDeadLock();TestDeadLock t2 = new TestDeadLock();t1.flag = 0;t2.flag = 1;Thread th1 = new Thread(t1);Thread th2 = new Thread(t2);th1.start();th2.start();}public void run() {System.out.println("flag:"+flag);if (flag == 1) {synchronized (o1) {try {Thread.sleep(500);} catch (Exception e) {}synchronized (o2) {System.out.println("th1");}}}if (flag == 0) {synchronized (o2) {try {Thread.sleep(500);} catch (Exception e) {}synchronized (o1) {System.out.println("th2");}}}}}