死锁实例
下面这道题，是考死锁的，比较简单，想两个问题：
1.什么时候会造成死锁
2.wait和notify释放了哪个锁，因为题目中有两个锁。
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import java.util.LinkedList;
public class DeadLockTest {
?? ?LinkedList list = new LinkedList(); ?
?? ? ?
??? public synchronized void push(Object x) { ?
?? ??? ?System.out.println("push");
??????? synchronized (list) { ?
??????????? list.addLast(x); ?
??????????? notify(); ?
??????? } ?
??? } ?
?
??? public synchronized Object pop() throws Exception {?? ?
??????? synchronized (list) { ?
??????????? if (list.size() <= 0) { ?
?????????? ??? ?wait(); ?
??????????? } ?
??????????? return list.removeLast(); ?
??????? } ?
??? } ?
?? ?
??? public static void main(String[] args) throws InterruptedException {
?? ??? ?final DeadLockTest deadLockTest = new DeadLockTest();
?? ??? ?Thread thread = new Thread(new Runnable() {
?? ??? ??? ?public void run() {
?? ??? ??? ??? ?try {
?? ??? ??? ??? ??? ?deadLockTest.pop();
?? ??? ??? ??? ?} catch (Exception e) {
?? ??? ??? ??? ??? ?// TODO Auto-generated catch block
?? ??? ??? ??? ??? ?e.printStackTrace();
?? ??? ??? ??? ?}
?? ??? ??? ?}
?? ??? ?});
?? ??? ?thread.start();
?? ??? ?Thread.sleep(2000);
?? ??? ?Thread threadPush = new Thread(new Runnable() {
?? ??? ??? ?public void run() {
?? ??? ??? ??? ?try {
?? ??? ??? ??? ??? ?deadLockTest.push("push thread");
?? ??? ??? ??? ?} catch (Exception e) {
?? ??? ??? ??? ??? ?// TODO Auto-generated catch block
?? ??? ??? ??? ??? ?e.printStackTrace();
?? ??? ??? ??? ?}
?? ??? ??? ?}
?? ??? ?});
?? ??? ?threadPush.start();
?? ??? ?
?? ?}
}
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显然当stack中没有元素时，pop的时候会释放this对象锁，当其它线程进行push或者pop时，list并没有释放，一直等待list的释放，但是wait又在等待其它线程唤醒，因此出现了死锁。
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