How to Enable Multithreaded Scheduled Tasks in Spring Boot

The author introduces the problem that Spring Boot's @EnableScheduling creates a single‑threaded scheduler by default, as the ScheduledTaskRegistrar falls back to Executors.newSingleThreadScheduledExecutor() when no taskScheduler is provided.

To run scheduled tasks concurrently, three solutions are presented:

1. Implement SchedulingConfigurer and set a custom scheduler

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

2. Configure the thread‑pool size via properties

spring.task.scheduling.pool.size=10

Adding this line to application.properties or application.yml changes the scheduler to a pool of the specified size.

3. Combine @Async with a custom ThreadPoolTaskExecutor

@Bean
public ThreadPoolTaskExecutor taskExecutor() {
    ThreadPoolTaskExecutor pool = new ThreadPoolTaskExecutor();
    pool.setCorePoolSize(4);
    pool.setMaxPoolSize(6);
    pool.setKeepAliveSeconds(120);
    pool.setQueueCapacity(40);
    pool.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
    pool.setWaitForTasksToCompleteOnShutdown(true);
    return pool;
}

After defining the executor, annotate the scheduled method with both @Async and @Scheduled:

@Async
@Scheduled(cron = "0/2 * * * * ?")
public void test2() {
    System.out.println("..................执行test2.................");
}

The article concludes by asking readers which method they prefer and includes a promotional note encouraging followers to like, share, and subscribe for additional PDF resources on Spring Cloud, Spring Boot, and MyBatis.