Using @Scheduled in Spring Boot for Task Scheduling: Configuration, Parameters, and Multi‑threading

Spring Boot provides the @Scheduled annotation to define scheduled tasks. The article shows how to configure tasks via application.properties , with examples of fixedDelayString and cron expressions, and emphasizes the necessity of the @EnableScheduling annotation.

package com.accord.task;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

/**
 * Load task information from configuration file
 * @author 王久印
 */
@Component
public class ScheduledTask {
    private static final SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");

    // @Scheduled(fixedDelayString = "${jobs.fixedDelay}")
    @Scheduled(fixedDelayString = "2000")
    public void getTask1() {
        System.out.println("任务1,从配置文件加载任务信息，当前时间：" + dateFormat.format(new Date()));
    }

    @Scheduled(cron = "${jobs.cron}")
    public void getTask2() {
        System.out.println("任务2,从配置文件加载任务信息，当前时间：" + dateFormat.format(new Date()));
    }
}

The corresponding application.properties entries are:

jobs.fixedDelay=5000
jobs.cron=0/5 * *  * * ?

The main application class must enable scheduling:

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

@SpringBootApplication
@EnableScheduling
public class SpringBootCron2Application {
    public static void main(String[] args) {
        SpringApplication.run(SpringBootCron2Application.class, args);
    }
}

The article lists the most common @Scheduled parameters:

@Scheduled(fixedRate=2000) – execute every 2 seconds after the previous start.

@Scheduled(fixedDelay=2000) – execute 2 seconds after the previous finish.

@Scheduled(initialDelay=1000, fixedDelay=2000) – wait 1 second before the first execution, then use fixed‑delay.

@Scheduled(cron="* * * * * ?") – execute according to a cron expression.

By default Spring Boot creates a single‑threaded executor for all scheduled tasks. To achieve concurrent execution, the article demonstrates implementing SchedulingConfigurer and providing a custom thread pool:

package com.accord.task;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.SchedulingConfigurer;
import org.springframework.scheduling.config.ScheduledTaskRegistrar;
import java.util.concurrent.Executors;

@Configuration
public class ScheduleConfig implements SchedulingConfigurer {
    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        // Set a thread pool with 10 threads for scheduled tasks
        taskRegistrar.setScheduler(Executors.newScheduledThreadPool(10));
    }
}

With this configuration, each scheduled method runs in a separate thread, as shown by the multi‑threaded execution screenshots. The article also includes a second example ( ScheduledTask2 ) that demonstrates fixedDelay , fixedRate , initialDelay , and cron usages, logging the execution count for each.

package com.accord.task;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class ScheduledTask2 {
    private Logger logger = LoggerFactory.getLogger(ScheduledTask2.class);
    private int fixedDelayCount = 1;
    private int fixedRateCount = 1;
    private int initialDelayCount = 1;
    private int cronCount = 1;

    @Scheduled(fixedDelay = 5000)
    public void testFixDelay() {
        logger.info("===fixedDelay: 第{}次执行方法", fixedDelayCount++);
    }

    @Scheduled(fixedRate = 5000)
    public void testFixedRate() {
        logger.info("===fixedRate: 第{}次执行方法", fixedRateCount++);
    }

    @Scheduled(initialDelay = 1000, fixedRate = 5000)
    public void testInitialDelay() {
        logger.info("===initialDelay: 第{}次执行方法", initialDelayCount++);
    }

    @Scheduled(cron = "0 0/1 * * * ?")
    public void testCron() {
        logger.info("===cron: 第{}次执行方法", cronCount++);
    }
}

Finally, the article reminds readers that without @EnableScheduling the scheduled methods will never be triggered, and it provides links to official documentation and an online cron expression generator.