Solving problems encountered by Springboot scheduled tasks

The content of this article is about solving problems encountered by Springboot scheduled tasks. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Foreword: When using Springboot to integrate scheduled tasks, I found that when a scheduled task takes too long to execute, it will block the execution of other scheduled tasks.

Problem Location

After checking the Springboot documentation and printing logs (outputting the current thread information), I learned that the problem is because Springboot uses only one thread to process scheduled tasks by default.

Problem Review

It should be noted that the Springboot version of the example is 2.1.3.RELEASE.

Key pom file configuration

    <!--继承父项目-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    
    ...省略非关键配置
    
    <!-- 引入依赖-->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

Timing task

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

/**
 * 定时任务
 * @author RJH
 * create at 2019-03-29
 */
@Component
public class SimpleTask {

    private static Logger logger= LoggerFactory.getLogger(SimpleTask.class);

    /**
     * 执行会超时的任务，定时任务间隔为5000ms(等价于5s)
     */
    @Scheduled(fixedRate = 5000)
    public void overtimeTask(){
        try {
            logger.info("current run by overtimeTask");
            //休眠时间为执行间隔的2倍
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    /**
     * 正常的定时任务
     */
    @Scheduled(fixedRate = 5000)
    public void simpleTask(){
        logger.info("current run by simpleTask");
    }
}

Startup class

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
public class TaskDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(TaskDemoApplication.class, args);
    }

}

Running results

...省略非关键信息
2019-03-29 21:22:38.410  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by simpleTask
2019-03-29 21:22:38.413  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by overtimeTask
2019-03-29 21:22:48.413  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by simpleTask
2019-03-29 21:22:48.414  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by overtimeTask
2019-03-29 21:22:58.418  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by simpleTask
2019-03-29 21:22:58.418  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by overtimeTask
2019-03-29 21:23:08.424  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by simpleTask
2019-03-29 21:23:08.424  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by overtimeTask
2019-03-29 21:23:18.425  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by simpleTask
2019-03-29 21:23:18.426  INFO 59731 --- [   scheduling-1] com.rjh.task.SimpleTask                  : current run by overtimeTask
...

Result analysis

It can be seen from the running results:

1. Every time the scheduled task is run, it is processed by scheduling-1This thread
2. runs normallysimpleTask was blocked by overtimeTask, which caused the running interval to become 10 seconds

. Later, I checked the documentation of Springboot I also learned that the default maximum number of running threads for scheduled tasks is 1.

Solution

Since the Springboot version used is 2.1.3.RELEASE, there are two ways to solve this problem

Use Springboot configuration

You can configure the number of threads available for scheduled tasks in the configuration file:

## 配置可用线程数为10
spring.task.scheduling.pool.size=10

Customize the thread pool of scheduled tasks

Use a custom thread pool Instead of the default thread pool

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.TaskScheduler;
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;

/**
 * 定时任务配置类
 * @author RJH
 * create at 2019-03-29
 */
@Configuration
public class ScheduleConfig {

    /**
     * 此处方法名为Bean的名字，方法名无需固定
     * 因为是按TaskScheduler接口自动注入
     * @return
     */
    @Bean
    public TaskScheduler taskScheduler(){
        // Spring提供的定时任务线程池类
        ThreadPoolTaskScheduler taskScheduler=new ThreadPoolTaskScheduler();
        //设定最大可用的线程数目
        taskScheduler.setPoolSize(10);
        return taskScheduler;
    }
}

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