package com.example.demo.thread;
/**
* @projectName: demo
* @package: com.example.demo.thread
* @className: TestDeath
* @author:
* @description: 测试死锁:多个线程互相拥有相同的资源会出现死锁现象
* @date: 2021/12/8 14:56
*/
public class TestDeath {
public static void main(String[] args) {
MakeUp zmakeUp = new MakeUp(1, "张三");
MakeUp lmakeUp = new MakeUp(0, "李三");
new Thread(zmakeUp).start();
new Thread(lmakeUp).start();
}
}
class MakeUp implements Runnable {
// static在创建对象前初始化，保证唯一性
static Lipstick lipstick = new Lipstick();
static Mirror mirror = new Mirror();
int choose;
String personName;
public MakeUp(int choose, String personName) {
this.choose = choose;
this.personName = personName;
}
@Override
public void run() {
if (choose == 0) {
synchronized (lipstick) {
System.out.println(personName + ":先使用口红化妆");
System.out.println("口红哈希" + lipstick.hashCode());
try {
Thread.sleep(1000);
synchronized (mirror) {
System.out.println(personName + ":再使用镜子化妆");
System.out.println("镜子哈希" + mirror.hashCode());
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
} else {
synchronized (mirror) {
System.out.println(personName + ":再使用镜子化妆");
System.out.println("镜子哈希" + mirror.hashCode());
try {
Thread.sleep(1000);
synchronized (lipstick) {
System.out.println(personName + ":先使用口红化妆");
System.out.println("口红哈希" + lipstick.hashCode());
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
class Lipstick {
}
class Mirror {
}
资源不放
上面样例解决方案
synchronized不要嵌套使用
package com.example.demo.thread;
/**
* @projectName: demo
* @package: com.example.demo.thread
* @className: TestDeath
* @author:
* @description: 测试死锁:synchronized块中不要出现另一个synchronized块
* @date: 2021/12/8 14:56
*/
public class TestDeath {
public static void main(String[] args) {
MakeUp zmakeUp = new MakeUp(1, "张三");
MakeUp lmakeUp = new MakeUp(0, "李三");
new Thread(zmakeUp).start();
new Thread(lmakeUp).start();
}
}
class MakeUp implements Runnable {
// static在创建对象前初始化，保证唯一性
static Lipstick lipstick = new Lipstick();
static Mirror mirror = new Mirror();
int choose;
String personName;
public MakeUp(int choose, String personName) {
this.choose = choose;
this.personName = personName;
}
@Override
public void run() {
if (choose == 0) {
synchronized (lipstick) {
System.out.println(personName + ":先使用口红化妆");
System.out.println("口红哈希" + lipstick.hashCode());
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (mirror) {
System.out.println(personName + ":再使用镜子化妆");
System.out.println("镜子哈希" + mirror.hashCode());
}
}
} else {
synchronized (mirror) {
System.out.println(personName + ":再使用镜子化妆");
System.out.println("镜子哈希" + mirror.hashCode());
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
synchronized (lipstick) {
System.out.println(personName + ":先使用口红化妆");
System.out.println("口红哈希" + lipstick.hashCode());
}
}
}
}
class Lipstick {
}
class Mirror {
}
image.png
