spring（3）定时任务小结

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本文链接： https://blog.csdn.net/m0_38060977/article/details/102756755

一 配置

spring的任务默认是单线程的，会有阻塞问题，所以需要配置线程池

<task:scheduler id="myScheduler" pool-size="5"/>

详见:spring定时任务详解（@Scheduled注解）

二 异步

@Async

参考:

• https://segmentfault.com/a/1190000015267976
  补充:

1. @Async会导致fixedDelay失效

	@Async
	@Scheduled(initialDelay=1000,fixedDelay=2000)
	public void test2() {
		logger.info(Thread.currentThread().getName()+"===test2 start");
		try {
			Thread.sleep(5000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		logger.info(Thread.currentThread().getName()+"===test2 end");
	}

结果:间隔两秒执行

2019-04-25 23:19:28.381  INFO 19272 --- [cTaskExecutor-1] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-1===test2 start
2019-04-25 23:19:30.371  INFO 19272 --- [cTaskExecutor-2] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-2===test2 start
2019-04-25 23:19:32.372  INFO 19272 --- [cTaskExecutor-3] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-3===test2 start
2019-04-25 23:19:33.381  INFO 19272 --- [cTaskExecutor-1] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-1===test2 end
2019-04-25 23:19:34.374  INFO 19272 --- [cTaskExecutor-4] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-4===test2 start
2019-04-25 23:19:35.372  INFO 19272 --- [cTaskExecutor-2] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-2===test2 end
2019-04-25 23:19:36.375  INFO 19272 --- [cTaskExecutor-5] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-5===test2 start
2019-04-25 23:19:37.373  INFO 19272 --- [cTaskExecutor-3] com.example.demo.task.Mytask             : SimpleAsyncTaskExecutor-3===test2 end

2. @Async会导致fixRate可以并发执行

springboot中的多线程并行应用

Spring定时任务并行(异步)处理

SchedulingConfigurer

1.实现动态定时任务

	@Override
	public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
		taskRegistrar.addFixedRateTask(() -> System.out.println("执行定时任务1: " + new Date()), 1000);
		TriggerTask triggrtTask = new TriggerTask( // 任务内容.拉姆达表达式
				() -> {System.out.println("执行定时任务2: " + new Date());},
				// 设置触发器，这里是一个拉姆达表达式，传入的TriggerContext类型，返回的是Date类型
				triggerContext -> {
					// 2.3 返回执行周期(Date)
					return new CronTrigger("*/2 * * * * ?").nextExecutionTime(triggerContext);
				});
 
		taskRegistrar.addTriggerTask(triggrtTask);
	}

参考:https://cloud.tencent.com/developer/article/1362794

2.实现并行，设置线程池

import org.springframework.scheduling.TaskScheduler; 
import org.springframework.scheduling.annotation.AsyncConfigurer; 
import org.springframework.scheduling.annotation.EnableAsync; 
import org.springframework.scheduling.annotation.EnableScheduling; 
import org.springframework.scheduling.annotation.SchedulingConfigurer; 
import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler; 
import org.springframework.scheduling.config.ScheduledTaskRegistrar;

@Configuration 
@EnableScheduling 
@EnableAsync( mode = AdviceMode.PROXY, proxyTargetClass = false, order=Ordered.HIGHEST_PRECEDENCE ) 
@ComponentScan( basePackages = “hello” ) 
public class RootContextConfiguration implements AsyncConfigurer, SchedulingConfigurer { 

@Bean 
public ThreadPoolTaskScheduler taskScheduler() { 
  ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler(); 
  scheduler.setPoolSize(20); 
  scheduler.setThreadNamePrefix(“task-“); 
  scheduler.setAwaitTerminationSeconds(60); 
  scheduler.setWaitForTasksToCompleteOnShutdown(true); 
  return scheduler; 
}

@Override 
public Executor getAsyncExecutor() { 
  Executor executor = this.taskScheduler(); 
  return executor; 
}

@Override 
public void configureTasks(ScheduledTaskRegistrar registrar) { 
  TaskScheduler scheduler = this.taskScheduler(); 
  registrar.setTaskScheduler(scheduler); 
} 
} 

AsyncConfigurer

主要也是配置线程池
SpringBoot 线程池配置 实现AsyncConfigurer接口

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