redis使用watch秒杀抢购思路

Posted 2020-10-15 devin.ou

1、使用watch，采用乐观锁 
2、不使用悲观锁，因为等待时间非常长，响应慢 
3、不使用队列，因为并发量会让队列内存瞬间升高

测试代码：

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import redis.clients.jedis.Jedis;

/**
 * redis测试抢购
 * 
 * @author 10255_000
 * 
 */
public class RedisTest {
    public static void main(String[] args) {
        final String watchkeys = "watchkeys";
        ExecutorService executor = Executors.newFixedThreadPool(20);

        final Jedis jedis = new Jedis("192.168.3.202", 6379);
        jedis.set(watchkeys, "0");// 重置watchkeys为0
        jedis.del("setsucc", "setfail");// 清空抢成功的，与没有成功的
        jedis.close();

        for (int i = 0; i < 10000; i++) {// 测试一万人同时访问
            executor.execute(new MyRunnable());
        }
        executor.shutdown();
    }
}

import java.util.List;
import java.util.UUID;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.Transaction;

public class MyRunnable implements Runnable {

    String watchkeys = "watchkeys";// 监视keys
    Jedis jedis = new Jedis("192.168.3.202", 6379);

    public MyRunnable() {
    }

    @Override
    public void run() {
        try {
            jedis.watch(watchkeys);// watchkeys

            String val = jedis.get(watchkeys);
            int valint = Integer.valueOf(val);
            String userifo = UUID.randomUUID().toString();
            if (valint < 10) {
                Transaction tx = jedis.multi();// 开启事务

                tx.incr("watchkeys");

                List<Object> list = tx.exec();// 提交事务，如果此时watchkeys被改动了，则返回null
                if (list != null) {
                    System.out.println("用户：" + userifo + "抢购成功，当前抢购成功人数:"
                            + (valint + 1));
                    /* 抢购成功业务逻辑 */
                    jedis.sadd("setsucc", userifo);
                } else {
                    System.out.println("用户：" + userifo + "抢购失败");
                    /* 抢购失败业务逻辑 */
                    jedis.sadd("setfail", userifo);
                }

            } else {
                System.out.println("用户：" + userifo + "抢购失败");
                jedis.sadd("setfail", userifo);
                // Thread.sleep(500);
                return;
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            jedis.close();
        }

    }

}