SpringBoot【注解 01】@Scheduled实现定时任务的串行和并行执行

06-15 1038阅读

在SpringBoot中，如果使用@Scheduled注解来定义多个定时任务，默认情况下这些任务将会被安排在一个单线程的调度器中执行。这意味着，这些任务将会串行执行，而不是并行执行。当一个任务正在执行时，其他被触发的任务将会等待当前任务完成后再开始执行，这可能导致任务执行上的阻塞，特别是当某个任务执行时间较长时，可能会延迟后续任务的启动时间，影响定时任务的准时性。

SpringBoot【注解 01】@Scheduled实现定时任务的串行和并行执行
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@Scheduled

  • 1.问题代码及测试结果
  • 2.定时任务实现并行
    • 2.1 使用自定义线程池（添加类）
    • 2.2 使用异步处理（添加类和注解）
    • 3.总结

      1.问题代码及测试结果

      问题代码：

          @Scheduled(cron = "*/1 * * * * *")
    public void a() throws InterruptedException {
        log.info("A Start {}!", System.currentTimeMillis());
        Thread.sleep(2000);
        log.info("A End {}!", System.currentTimeMillis());
    }
    @Scheduled(cron = "*/1 * * * * *")
    public void b() {
        log.info("B Start {}!", System.currentTimeMillis());
        log.info("B End {}!", System.currentTimeMillis());
    }

      部分测试结果：

      15:38:29.001 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716968309001!
15:38:29.001 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716968309001!
15:38:29.001 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716968309001!
15:38:31.003 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716968311003!
15:38:31.003 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716968311003!
15:38:31.003 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716968311003!
15:38:32.002 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716968312002!
15:38:34.003 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716968314003!
15:38:34.003 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716968314003!
15:38:34.003 [scheduling-1] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716968314003!

      结果分析：

      • A和B是串行的。

        2.定时任务实现并行

        2.1 使用自定义线程池（添加类）

        可以通过配置一个自定义的TaskScheduler或者ThreadPoolTaskScheduler来为@Scheduled任务提供一个线程池，从而允许多个任务并行执行。例如，可以在配置类中定义一个ThreadPoolTaskScheduler Bean：

        @Configuration
public class AsyncConfig {
    @Bean
    public ThreadPoolTaskScheduler taskScheduler() {
        ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
        // 设置线程池大小
        scheduler.setPoolSize(10); 
        scheduler.setThreadNamePrefix("my-scheduled-task-");
        return scheduler;
    }
}

        并确保你的配置类被扫描到，且在@EnableScheduling注解的上下文中。

        测试代码：

            @Scheduled(cron = "*/1 * * * * *")
    public void a() throws InterruptedException {
        log.info("A Start {}!", System.currentTimeMillis());
        Thread.sleep(2000);
        log.info("A End {}!", System.currentTimeMillis());
    }
    @Scheduled(cron = "*/1 * * * * *")
    public void b() {
        log.info("B Start {}!", System.currentTimeMillis());
        log.info("B End {}!", System.currentTimeMillis());
    }

        部分测试结果：

        15:16:18.003 [my-scheduled-task-2] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716966978003!
15:16:18.003 [my-scheduled-task-1] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716966978003!
15:16:18.003 [my-scheduled-task-1] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716966978003!
15:16:19.002 [my-scheduled-task-1] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716966979002!
15:16:19.002 [my-scheduled-task-1] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716966979002!
15:16:20.004 [my-scheduled-task-2] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716966980004!
15:16:20.004 [my-scheduled-task-3] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716966980004!
15:16:20.004 [my-scheduled-task-3] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716966980004!
15:16:21.003 [my-scheduled-task-1] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716966981003!
15:16:21.003 [my-scheduled-task-4] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716966981003!
15:16:21.003 [my-scheduled-task-4] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716966981003!
15:16:22.001 [my-scheduled-task-2] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716966982001!
15:16:22.001 [my-scheduled-task-2] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716966982001!
15:16:23.004 [my-scheduled-task-1] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716966983004!
15:16:23.004 [my-scheduled-task-3] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716966983004!
15:16:23.004 [my-scheduled-task-3] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716966983004!

        结果分析：

        • A和B是并行的；
        • A和A或者B和B是串行的。

          2.2 使用异步处理（添加类和注解）

          结合@Async注解和@EnableAsync可以使得每个@Scheduled任务在独立的线程中异步执行。

          首先需要在配置类中启用异步支持，并配置一个线程池，然后在每个定时任务方法上添加@Async注解。

          @EnableAsync
@Configuration
public class AsyncConfig {
    @Bean
    public Executor taskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(10);
        executor.setMaxPoolSize(20);
        executor.setQueueCapacity(200);
        executor.setThreadNamePrefix("Async-");
        executor.initialize();
        return executor;
    }
}

          测试代码：

              @Async
    @Scheduled(cron = "*/1 * * * * *")
    public void a() throws InterruptedException {
        log.info("A Start {}!", System.currentTimeMillis());
        Thread.sleep(2000);
        log.info("A End {}!", System.currentTimeMillis());
    }
    @Async
    @Scheduled(cron = "*/1 * * * * *")
    public void b() {
        log.info("B Start {}!", System.currentTimeMillis());
        log.info("B End {}!", System.currentTimeMillis());
    }

          部分测试结果：

          15:26:52.008 [Async-2] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716967612008!
15:26:52.008 [Async-1] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716967612008!
15:26:52.009 [Async-1] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716967612009!
15:26:53.002 [Async-4] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716967613002!
15:26:53.002 [Async-3] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716967613002!
15:26:53.002 [Async-3] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716967613002!
15:26:54.001 [Async-6] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716967614001!
15:26:54.001 [Async-5] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716967614001!
15:26:54.001 [Async-5] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716967614001!
15:26:54.010 [Async-2] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716967614010!
15:26:55.002 [Async-8] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716967615002!
15:26:55.002 [Async-7] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716967615002!
15:26:55.002 [Async-7] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716967615002!
15:26:55.002 [Async-4] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716967615002!
15:26:56.001 [Async-10] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716967616001!
15:26:56.001 [Async-9] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716967616001!
15:26:56.001 [Async-9] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716967616001!
15:26:56.002 [Async-6] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716967616002!
15:26:57.001 [Async-3] INFO  c.x.e.m.SchedulerTask - [a,44] - A Start 1716967617001!
15:26:57.001 [Async-1] INFO  c.x.e.m.SchedulerTask - [b,52] - B Start 1716967617001!
15:26:57.001 [Async-1] INFO  c.x.e.m.SchedulerTask - [b,53] - B End 1716967617001!
15:26:57.002 [Async-8] INFO  c.x.e.m.SchedulerTask - [a,46] - A End 1716967617002!

          测试结果分析：

          • A和B是并行的；
          • A和A或者B和B也是并行的。

            3.总结

            如有错误，请小伙伴儿们不吝赐教。

            定时任务有不同的需求，使用串行还是并行要结合业务进行选择。

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