java中Lock锁测试

浅浅的花香味﹌ 2023-08-17 17:05 91阅读 0赞

1.不加锁

public class Threads implements Runnable {
        // 定义去北京火车票
        private Integer tickets = 10;
        // 定义去武汉火车票
        private Integer tic = 10;
        // 定义锁对象
        private Lock lock = new ReentrantLock();
        @Override
        public void run() {
            while (true) {
                try {
                    Thread.sleep(1000);
                    if (tickets > 0) {
                        System.out.println(Thread.currentThread().getName() + "正在出售第" + tickets-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
                try {
                   // lock.lock(); //加锁
                    Thread.sleep(1000);
                    if (tic > 0) {
                        System.out.println(Thread.currentThread().getName() + "-------->>>>>>正在出售第" + tic-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }finally {
                    //lock.unlock();//释放锁
                }
            }
        }
    
        public static void main(String[] args) {
            Threads s = new Threads();
            Thread t1 = new Thread(s, "窗口1");
            Thread t2 = new Thread(s, "窗口2");
            Thread t3 = new Thread(s, "窗口3");
            Thread t4 = new Thread(s, "窗口4");
            Thread t5 = new Thread(s, "窗口5");
            Thread t6 = new Thread(s, "窗口6");
            Thread t7 = new Thread(s, "窗口7");
            Thread t8 = new Thread(s, "窗口8");
            Thread t9 = new Thread(s, "窗口9");
            Thread t10 = new Thread(s, "窗口10");
            t1.start();
            t2.start();
            t3.start();
            t4.start();
            t5.start();
            t6.start();
            t7.start();
            t8.start();
            t9.start();
            t10.start();
        }
    }

1.都在疯狂超卖

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70][]

2.锁住线程整个方法

/**
     * @author : zhang sq
     * @date : 2019/9/26 9:22
     * 线程锁
     **/
    public class Threads implements Runnable {
        // 定义去北京火车票
        private Integer tickets = 15;
        // 定义去武汉火车票
        private Integer tic = 15;
        // 定义锁对象
        private Lock lock = new ReentrantLock();
        @Override
        public void run() {
            while (true) {
                try {
                    lock.lock(); //加锁
                    Thread.sleep(1000);
                    if (tickets > 0) {
                        System.out.println(Thread.currentThread().getName() + "正在出售第" + tickets-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
                try {
                    Thread.sleep(1000);
                    if (tic > 0) {
                        System.out.println(Thread.currentThread().getName() + "-------->>>>>>正在出售第" + tic-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    lock.unlock(); //释放锁
                }
            }
        }
    
        public static void main(String[] args) {
            Threads s = new Threads();
            Thread t1 = new Thread(s, "窗口1");
            Thread t2 = new Thread(s, "窗口2");
            Thread t3 = new Thread(s, "窗口3");
            Thread t4 = new Thread(s, "窗口4");
            Thread t5 = new Thread(s, "窗口5");
            Thread t6 = new Thread(s, "窗口6");
            Thread t7 = new Thread(s, "窗口7");
            Thread t8 = new Thread(s, "窗口8");
            Thread t9 = new Thread(s, "窗口9");
            Thread t10 = new Thread(s, "窗口10");
            t1.start();
            t2.start();
            t3.start();
            t4.start();
            t5.start();
            t6.start();
            t7.start();
            t8.start();
            t9.start();
            t10.start();
        }
    }

2.结果: 没得问题

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70 1][]

3.锁住下半段

public void run() {
            while (true) {
                try {
                    Thread.sleep(1000);
                    if (tickets > 0) {
                        System.out.println(Thread.currentThread().getName() + "正在出售第" + tickets-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
                try {
                    lock.lock(); //加锁
                    Thread.sleep(1000);
                    if (tic > 0) {
                        System.out.println(Thread.currentThread().getName() + "-------->>>>>>正在出售第" + tic-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }finally {
                    lock.unlock();//释放锁
                }
            }
        }

3.结果上面超卖,下面没超卖

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70 2][]

4.锁住上半段

@Override
        public void run() {
            while (true) {
                try {
                    lock.lock(); //加锁
                    Thread.sleep(1000);
                    if (tickets > 0) {
                        System.out.println(Thread.currentThread().getName() + "正在出售第" + tickets-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }finally {
                    lock.unlock();//释放锁
                }
                try {
    
                    Thread.sleep(1000);
                    if (tic > 0) {
                        System.out.println(Thread.currentThread().getName() + "-------->>>>>>正在出售第" + tic-- + "张票");
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

4.都挺好,都没有超卖.(???因为上半段只能进一个线程,导致下半段安全? 求大佬解答)

.![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70 3][]

求教!对于下订单  里面业务复杂库存容易超卖, 是只需要锁住下单方法中减库存那一块的方法?还是锁住整个下订单方法?

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70]: /images/20230808/8720bddc12b8438b99eee4c54d958990.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70 1]: /images/20230808/730790af0abd4c35a76c6c160efccf83.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70 2]: /images/20230808/b1298742b2cc4ee6a757d80579771716.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nc2hlbmdxaWFuZzE2OA_size_16_color_FFFFFF_t_70 3]: /images/20230808/9689d2e1edd54dcdb6865ecbd4c5af11.png