第關(guān)于@Scheduled注解的任務(wù)為什么不執(zhí)行的問題目錄概述舉例說明原因分析解決方案

概述

在SpringBoot中可以通過@Scheduled來注解定義一個定時任務(wù)，但是有時候你可能發(fā)現(xiàn)有的定時任務(wù)道理時間卻沒有執(zhí)行，但是又不是每次都不執(zhí)行，為什么呢？？？

舉例說明

下面這段diam定義了一個沒隔10s執(zhí)行一次的定時任務(wù)：

packagecom.study.practice.schedule;

importlombok.extern.slf4j.Slf4j;

importorg.springframework.scheduling.annotation.Scheduled;

importorg.springframework.stereotype.Component;

*@Description:schedule測試

*@Version:V1.0.0

*@Date:2025/12/111:22

@Component

@Slf4j

publicclassScheduleTest{

@Scheduled(cron="0/10****")

publicvoidexecute(){

("Scheduledtaskisrunning......");

}

}

記得在啟動類或者Configuration類上添加了@EnableScheduling注解。

啟動應(yīng)用，控制臺每隔10秒打印一條日志：

2025-12-0111:27:00.002INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:27:10.001INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:27:20.002INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:27:30.001INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:27:40.002INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:27:50.001INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:28:00.002INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:28:10.002INFO97876---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

但是，問題才剛剛開始。

在上面的相關(guān)代碼中，我們使用cron表達(dá)式指定的定時任務(wù)執(zhí)行時間點(diǎn)從0秒開始，每隔10s執(zhí)行一次，現(xiàn)在我們再加一個定時任務(wù)：

packagecom.study.practice.schedule;

importlombok.extern.slf4j.Slf4j;

importorg.springframework.scheduling.annotation.Scheduled;

importorg.springframework.stereotype.Component;

importjava.util.concurrent.TimeUnit;

*@Description:schedule測試

*@Version:V1.0.0

*@Date:2025/12/111:22

@Component

@Slf4j

publicclassScheduleTestTwo{

@Scheduled(cron="0/10*****")

publicvoidsecond()throwsInterruptedException{

("Secondscheduledtaskisrunning......");

TimeUnit.SECONDS.sleep(5);

}

}

啟動項目，執(zhí)行結(jié)果如下：

2025-12-0111:36:30.001INFO134576---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:36:30.002INFO134576---[scheduling-1]c.s.practice.schedule.ScheduleTestTwo:Secondscheduledtaskisrunning......

2025-12-0111:36:40.002INFO134576---[scheduling-1]c.s.practice.schedule.ScheduleTestTwo:Secondscheduledtaskisrunning......

2025-12-0111:36:45.002INFO134576---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:36:50.001INFO134576---[scheduling-1]c.s.practice.schedule.ScheduleTestTwo:Secondscheduledtaskisrunning......

2025-12-0111:36:55.002INFO134576---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

2025-12-0111:37:00.001INFO134576---[scheduling-1]c.s.practice.schedule.ScheduleTestTwo:Secondscheduledtaskisrunning......

2025-12-0111:37:05.001INFO134576---[scheduling-1]c.study.practice.schedule.ScheduleTest:Scheduledtaskisrunning......

可以看到任務(wù)1和任務(wù)2本該都是每個10s執(zhí)行，但是卻發(fā)現(xiàn)只有任務(wù)2執(zhí)行了，任務(wù)1卻等待了5s之后才執(zhí)行。

原因分析

為了找到原因，我們從@Scheduled注解的源碼開始分析：

下面是@Scheduled注解的注釋：

*

*pProcessingof{@code@Scheduled}annotationsisperformedby

*registeringa{@linkScheduledAnnotationBeanPostProcessor}.Thiscanbe

*donemanuallyor,moreconveniently,throughthe{@codetask:annotation-driven/}

*elementor@{@linkEnableScheduling}annotation.

*

劃重點(diǎn),每一個有@Scheduled注解的方法都會被注冊為一個ScheduledAnnotationBeanPostProcessor,再接著往下看ScheduledAnnotationBeanPostProcessor:

/**

*Setthe{@linkorg.springframework.scheduling.TaskScheduler}thatwillinvoke

*thescheduledmethods,ora{@linkjava.util.concurrent.ScheduledExecutorService}

*tobewrappedasaTaskScheduler.

*pIfnotspecified,defaultschedulerresolutionwillapply:searchingfora

*unique{@linkTaskScheduler}beaninthecontext,orfora{@linkTaskScheduler}

*beannamed"taskScheduler"otherwise;thesamelookupwillalsobeperformedfor

*a{@linkScheduledExecutorService}bean.Ifneitherofthetwoisresolvable,

*alocalsingle-threadeddefaultschedulerwillbecreatedwithintheregistrar.

*@see#DEFAULT_TASK_SCHEDULER_BEAN_NAME

*/

publicvoidsetScheduler(Objectscheduler){

this.scheduler=scheduler;

}

重點(diǎn)來了，注意這句話：

ifneitheroftwoisresolvable,alocalsingle-threaddefaultschedulerwillbecreatedwithinintheregistrar.

這句話意味著，如果我們不主動配置我們需要的TaskScheduler，SpringBoot會默認(rèn)使用一個單線程的scheduler來處理我們用@Scheduled注解實現(xiàn)的定時任務(wù)，到此我們剛才的問題就可以理解了。

因為是單個線程執(zhí)行所有的定時任務(wù)，所有task2如果先執(zhí)行，因為執(zhí)行中等待了5s，所以task2執(zhí)行完后，task1接著繼續(xù)執(zhí)行。

解決方案

搞清楚這個流程后，解決這個問題就很簡單了。

根據(jù)剛才注釋的描述，我們只需要提供一個滿足自己需要的TaskScheduler并注冊到context容器中就可以了。

packagecom.study.practice.config;

importorg.springframework.context.annotation.Configuration;

importorg.springframework.scheduling.annotation.SchedulingConfigurer;

importorg.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;

importorg.springframework.scheduling.config.ScheduledTaskRegistrar;

*@Description:scheduler配置類

*@Version:V1.0.0

*@Date:2025/12/114:00

@Configuration

publicclassScheduledTaskConfigimplementsSchedulingConfigurer{

@Override

publicvoidconfigureTasks(ScheduledTaskRegistrartaskRegistrar){

ThreadPoolTaskSchedulertaskScheduler=newThreadPoolTaskScheduler();

taskScheduler.setPoolSize(2);

taskScheduler.initialize();

taskRegistrar.setTaskScheduler(taskScheduler);

}

}

上面的代碼提供了一個線程池大小為2的taskScheduler，再次啟動SpringBoot查看效果。

2025-12-0114:05:20.001INFO39768---[TaskScheduler-2]c.s.practice.schedule.ScheduleTestTwo:Secondscheduledtaskisrunning......

2025-12-0114:05:20.001INFO39768---[TaskScheduler-1]c.study.prac