新手求教死锁问题
[code=Java][/code]
public class TestDeadLock implements Runnable
{
public int flag = 1;
public Object o1 = new Object ();
public Object o2 = new Object ();

public void run () {
System.out.println ( "flag = " + flag);

if (flag == 1) {
synchronized (o1) {
try {
Thread.sleep(5000);
}
catch (Exception e) {
e.printStackTrace ();
}
}

synchronized (o2) {
System.out.println ("1");
}
}

if (flag == 0) {
synchronized (o2) {
try {
Thread.sleep(5000);
}
catch (Exception e1) {
e1.printStackTrace ();
}
}

synchronized (o1) {
System.out.println ("0");
}
}
}

public static void main(String[] args) {
TestDeadLock tdk1 = new TestDeadLock ();
TestDeadLock tdk2 = new TestDeadLock ();
tdk1.flag = 1;
tdk2.flag = 0;

Thread t1 = new Thread (tdk1);
Thread t2 = new Thread (tdk2);

t1.start();
t2.start();
}
}


为什么结果总是
flag = 1
flag = 0
1
0
而没有形成死锁啊？？？？？

------解决方案--------------------
hi guy, (sorry, no chinese input typer)
first:you have created two different objects of Class TestDeadLock, they don't need to share a "sharing resource";
second: you didn't really lock o2

if you want to test deadlock try to change the code as bellow:


code=Java]public class TestDeadLock implements Runnable {
public int flag = 1;
public static Object o1 = new Object();
public static Object o2 = new Object();

public void run() {
System.out.println("flag = " + flag + "" + this + ">time:" + System.currentTimeMillis());

if (flag == 1) { // 1, lock o1 first
synchronized (o1) {
try {
Thread.sleep(5000);
} catch (Exception e) {
e.printStackTrace();
}

synchronized (o2) {
System.out.println("1");
}
}


}

if (flag == 0) { // 0 lock o2 first
synchronized (o2) {
try {
Thread.sleep(5000);
} catch (Exception e1) {
e1.printStackTrace();
}

synchronized (o1) {
System.out.println("0");
}
}


}
}

public static void main(String[] args) {
TestDeadLock tdk1 = new TestDeadLock ();
TestDeadLock tdk2 = new TestDeadLock ();
tdk1.flag = 0;
tdk2.flag = 1;

Thread t1 = new Thread(tdk1);
Thread t2 = new Thread(tdk2);

t1.start();
t2.start();
}
}[/code]
------解决方案--------------------
public int flag = 1;
public Object o1 = new Object ();
public Object o2 = new Object ();

如上3个你定义的变量是成员变量，并非类变量，这在该类的不同实例间显然是互不影响的。用static修饰下就能看到效果了
------解决方案--------------------
那个例子只是可能出现死锁 我这个例子出现死锁的几率更大一些

Java code

package example;

import java.util.concurrent.atomic.AtomicInteger;

public class DeathLockExample {
    public static void main(String[] args) {
        final AtomicInteger x = new AtomicInteger(0);
        final AtomicInteger y = new AtomicInteger(0);

        new Thread() {
            public void run() {
                while (true) {
                    synchronized (x) {
                        synchronized (y) {
                            x.addAndGet(1);
                        }
                    }
                    System.err.println("x " + x.toString());
                }
            }
        }.start();

        new Thread() {
            public void run() {
                while (true) {
                    synchronized (y) {
                        synchronized (x) {
                            y.addAndGet(1);
                        }
                    }
                    System.err.println("y " + y.toString());
                }
            }
        }.start();
    }
}