SummerVocation_Learning--java的線程死結

標籤：div   sys   lock   print   style   syn   tac   try   deadlock   

 1   2 public class Test_DeadLock implements Runnable { 3   4     public int flag = 1; 5     static Object o1 = new Object(),o2 = new Object(); 6     public void run() { 7         System.out.println("flag= " + flag); 8         if (flag == 1) { 9             synchronized (o1) {  //o1鎖定10                 try {11                     Thread.sleep(500);12                 } catch (Exception e) {13                     e.printStackTrace();14                 }15             synchronized (o2) { //只要再鎖定o2，就能列印出1.16                 System.out.println("1"); //但是o2被另一個線程鎖定了，所以列印不出1.17                 }18             }19         }20         if (flag == 0) {21             synchronized (o2) { //鎖定o222                 try {23                     Thread.sleep(500);24                 } catch (Exception e) {25                     e.printStackTrace();26                 }27             synchronized (o1) {  //只要再等待鎖定o1，就能列印出0.28                     System.out.println("0"); //但是o1另一個線程鎖定，無法執行。兩個線程被鎖死，誰都無法完成執行。29                 }30             }31         }32     }33     34     public static void main(String[] args) {35         Test_DeadLock t1 = new Test_DeadLock();36         Test_DeadLock t2 = new Test_DeadLock();37         t1.flag = 1;38         t2.flag = 0;39         Thread t11 = new Thread(t1);40         Thread t21 = new Thread(t2);41         t11.start(); t21.start();42  43     }44     /*45      * flag= 146        flag= 047                 兩個線程產生死結，synchronized的輸出語句未被執行。48      */49  50 }

 

SummerVocation_Learning--java的線程死結