Springboot的异步线程池图鉴

Posted 2021-02-08 玲珑塔

1：定义线程池

@EnableAsync
    @Configuration
    class TaskPoolConfig {
 
        @Bean("taskExecutor")
        public Executor taskExecutor() {
            ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
            executor.setCorePoolSize(10);
            executor.setMaxPoolSize(20);
            executor.setQueueCapacity(200);
            executor.setKeepAliveSeconds(60);
            executor.setThreadNamePrefix("taskExecutor-");
            executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
executor.setWaitForTasksToCompleteOnShutdown(true);
         executor.setAwaitTerminationSeconds(60);
 return executor;
    }
}

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2：如何使用该线程池呢？

@Slf4j
@Component
public class Task {
 
    public static Random random = new Random();
@Autowired
    private StringRedisTemplate stringRedisTemplate;
@Async("taskExecutor")
    public void doTaskOne() throws Exception {
        log.info("开始做任务一");
        long start = System.currentTimeMillis();
        Thread.sleep(random.nextInt(10000));
        long end = System.currentTimeMillis();        log.info(stringRedisTemplate.randomKey());
        log.info("完成任务一，耗时：" + (end - start) + "毫秒");
    }
 
    @Async("taskExecutor")
    public void doTaskTwo() throws Exception {
        log.info("开始做任务二");
        long start = System.currentTimeMillis();
        Thread.sleep(random.nextInt(10000));
        long end = System.currentTimeMillis();
        log.info("完成任务二，耗时：" + (end - start) + "毫秒");
    }
 
    @Async("taskExecutor")
    public void doTaskThree() throws Exception {
        log.info("开始做任务三");
        long start = System.currentTimeMillis();
        Thread.sleep(random.nextInt(10000));
        long end = System.currentTimeMillis();
        log.info("完成任务三，耗时：" + (end - start) + "毫秒");
    }
 
}

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3 执行异步任务

@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest
public class ApplicationTests {
 
    @Autowired
    private Task task;
 
    @Test
    public void test() throws Exception {
 
        task.doTaskOne();
        task.doTaskTwo();
        task.doTaskThree();
 
        Thread.currentThread().join();
    }
 
}

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4 打印结果

2018-03-27 22:01:15.620  INFO 73703 --- [ taskExecutor-1] com.didispace.async.Task  : 开始做任务一

2018-03-27 22:01:15.620  INFO 73703 --- [ taskExecutor-2] com.didispace.async.Task  : 开始做任务二
2018-03-27 22:01:15.620  INFO 73703 --- [ taskExecutor-3] com.didispace.async.Task  : 开始做任务三
2018-03-27 22:01:18.165  INFO 73703 --- [ taskExecutor-2] com.didispace.async.Task  : 完成任务二，耗时：2545毫秒
2018-03-27 22:01:22.149  INFO 73703 --- [ taskExecutor-3] com.didispace.async.Task  : 完成任务三，耗时：6529毫秒
2018-03-27 22:01:23.912  INFO 73703 --- [ taskExecutor-1] com.didispace.async.Task  : 完成任务一，耗时：8292毫秒

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5 注意事项

注： @Async所修饰的函数不要定义为static类型，这样异步调用不会生效

从异常信息JedisConnectionException: Could not get a resource from the pool来看，我们很容易的可以想到，在应用关闭的时候异步任务还在执行，由于Redis连接池先销毁了，导致异步任务中要访问Redis的操作就报了上面的错。所以，我们得出结论，上面的实现方式在应用关闭的时候是不优雅的，那么我们要怎么做呢？如下设置：

executor.setWaitForTasksToCompleteOnShutdown(true);

executor.setAwaitTerminationSeconds(60);