测试Spring Boot定时任务冲突时，使用的线程数量
引入依赖：
Spring Boot 2.6.1
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
简单的测试类
import lombok.extern.slf4j.Slf4j;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
/**
* @author Song Jiangtao
* @date 2021/12/22
* @description:
*/
@Component
@Slf4j
public class Task {
@Scheduled(cron="*/2 * * * * ?")
public void process(){
log.info("do something");
}
@Scheduled(fixedRate = 2000)
public void currentTime(){
log.info("做点什么");
}
}
启动类开启定时任务：@EnableScheduling
测试结果如下：
由结果可见，main线程启动以后和scheduling-1线程跑了两个任务
由此可见，Spring Boot 定时器 默认是 单线程
我们新增两个定时任务来看看这样会有什么后果
@Scheduled(cron="*/2 * * * * ?")
public void process2() throws InterruptedException {
Thread.sleep(5000L);
log.info("do something use long time");
}
@Scheduled(cron="*/2 * * * * ?")
public void process3() throws InterruptedException {
Thread.sleep(10000L);
log.info("do something use long long time");
}
2021-12-22 16:30:28.735 INFO 14520 --- [ main] c.e.s.SpringBootScheduledApplication : Starting SpringBootScheduledApplication using Java 1.8.0_202 on TCZ-D with PID 14520 (D:\code\SpringBootScheduled\target\classes started by Administrator in D:\code\SpringBootScheduled) 2021-12-22 16:30:28.738 INFO 14520 --- [ main] c.e.s.SpringBootScheduledApplication : No active profile set, falling back to default profiles: default 2021-12-22 16:30:29.315 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:29.318 INFO 14520 --- [ main] c.e.s.SpringBootScheduledApplication : Started SpringBootScheduledApplication in 0.937 seconds (JVM running for 3.068) 2021-12-22 16:30:30.002 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : do something 2021-12-22 16:30:40.003 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : do something use long long time 2021-12-22 16:30:45.005 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : do something use long time 2021-12-22 16:30:45.005 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:45.005 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : do something 2021-12-22 16:30:45.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:45.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:45.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:45.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:45.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:55.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : do something use long long time 2021-12-22 16:30:55.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:55.006 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:30:55.007 INFO 14520 --- [ scheduling-1] c.e.springbootscheduled.scheduled.Task : do something
很明显任务会发生错乱，严重时会导致线程阻塞，最后崩溃
解决方法：引入线程池
新增配置类，配置线程池
package com.example.springbootscheduled.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import java.util.concurrent.ThreadPoolExecutor;
/**
* @author Song Jiangtao
* @date 2021/12/22
* @description:
*/
@Configuration
@EnableAsync
public class TaskConfig {
/**
* 默认线程数
*/
private static final int corePoolSize = 10;
/**
* 最大线程数
*/
private static final int maxPoolSize = 100;
/**
* 允许线程空闲时间（单位：默认为秒）,十秒后就把线程关闭
*/
private static final int keepAliveTime = 10;
/**
* 缓冲队列数
*/
private static final int queueCapacity = 200;
/**
* 线程池名前缀
*/
private static final String threadNamePrefix = "task-thread-";
/**
* bean的名称，默认为 首字小写 方法名
*/
@Bean("taskExecutor")
public ThreadPoolTaskExecutor getThread() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(corePoolSize);
executor.setMaxPoolSize(maxPoolSize);
executor.setQueueCapacity(keepAliveTime);
executor.setKeepAliveSeconds(queueCapacity);
executor.setThreadNamePrefix(threadNamePrefix);
//线程池拒绝策略
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
executor.initialize();
return executor;
}
}
每个定时任务添加注解 @Async("taskExecutor")
@Async("taskExecutor")
@Scheduled(fixedRate = 2000)
public void currentTime(){
log.info("做点什么");
}
启动测试
2021-12-22 16:41:36.141 INFO 19424 --- [ main] c.e.s.SpringBootScheduledApplication : Starting SpringBootScheduledApplication using Java 1.8.0_202 on TCZ-D with PID 19424 (D:\code\SpringBootScheduled\target\classes started by Administrator in D:\code\SpringBootScheduled) 2021-12-22 16:41:36.143 INFO 19424 --- [ main] c.e.s.SpringBootScheduledApplication : No active profile set, falling back to default profiles: default 2021-12-22 16:41:36.991 INFO 19424 --- [ main] c.e.s.SpringBootScheduledApplication : Started SpringBootScheduledApplication in 1.325 seconds (JVM running for 3.392) 2021-12-22 16:41:37.008 INFO 19424 --- [ task-thread-1] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:41:38.001 INFO 19424 --- [ task-thread-2] c.e.springbootscheduled.scheduled.Task : do something 2021-12-22 16:41:38.991 INFO 19424 --- [ task-thread-5] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:41:40.003 INFO 19424 --- [ task-thread-8] c.e.springbootscheduled.scheduled.Task : do something 2021-12-22 16:41:40.991 INFO 19424 --- [ task-thread-9] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:41:42.001 INFO 19424 --- [ task-thread-10] c.e.springbootscheduled.scheduled.Task : do something 2021-12-22 16:41:42.989 INFO 19424 --- [ task-thread-5] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:41:43.002 INFO 19424 --- [ task-thread-3] c.e.springbootscheduled.scheduled.Task : do something use long time 2021-12-22 16:41:44.002 INFO 19424 --- [ task-thread-9] c.e.springbootscheduled.scheduled.Task : do something 2021-12-22 16:41:44.990 INFO 19424 --- [ task-thread-5] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:41:45.002 INFO 19424 --- [ task-thread-6] c.e.springbootscheduled.scheduled.Task : do something use long time 2021-12-22 16:41:46.001 INFO 19424 --- [ task-thread-9] c.e.springbootscheduled.scheduled.Task : do something 2021-12-22 16:41:46.990 INFO 19424 --- [ task-thread-6] c.e.springbootscheduled.scheduled.Task : 做点什么 2021-12-22 16:41:47.002 INFO 19424 --- [ task-thread-1] c.e.springbootscheduled.scheduled.Task : do something use long time 2021-12-22 16:41:48.002 INFO 19424 --- [ task-thread-4] c.e.springbootscheduled.scheduled.Task : do something use long long time
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