SpringBoot使用@Scheduled实现定时任务的并行执行_Java

引言

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。

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：