SpringBoot异步任务详解

朱雀 2022-10-02 10:57 209阅读 0赞

### SpringBoot版本 ###

<groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.7.RELEASE</version>

### 定义异步任务 ###

package com.ming.asyncservice;
    
    import org.springframework.scheduling.annotation.Async;
    import org.springframework.stereotype.Component;
    
    @Component
    @Async
    public class AsyncTask { 
    
        public void task1() throws InterruptedException { 
            long start = System.currentTimeMillis();
            Thread.sleep(3000);
            long end = System.currentTimeMillis();
            System.out.println("当前线程：" + Thread.currentThread().getName() + "，" + "任务一耗时：" + (end - start) + "ms");
        }
    
        public void task2() throws InterruptedException { 
            long start = System.currentTimeMillis();
            Thread.sleep(3000);
            long end = System.currentTimeMillis();
            System.out.println("当前线程：" + Thread.currentThread().getName()  + "，" + "任务二耗时：" + (end - start) + "ms");
        }
    
        public void task3() throws InterruptedException { 
            long start = System.currentTimeMillis();
            Thread.sleep(3000);
            long end = System.currentTimeMillis();
            System.out.println("当前线程：" + Thread.currentThread().getName() + "，" + "任务三耗时：" + (end - start) + "ms");
        }

### 调用异步任务 ###

package com.ming.asyncservice;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class TaskService { 
    
        @Autowired
        private AsyncTask asyncTask;
    
        @RequestMapping("/taskService")
        public String doTask() throws InterruptedException { 
    
            long start = System.currentTimeMillis();
            asyncTask.task1();
            asyncTask.task2();
            asyncTask.task3();
            long end = System.currentTimeMillis();
            System.out.println("任务总耗时：" + (end - start) + "ms");
            return "任务总耗时：" + (end - start) + "ms";
        }
    }

### 开启异步任务 ###

package com.ming;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.scheduling.annotation.EnableAsync;
    
    @EnableAsync
    @SpringBootApplication
    public class ScheduleTaskApplication { 
    
        public static void main(String[] args) { 
        
            SpringApplication.run(ScheduleTaskApplication.class, args);
        }

### 测试结果 ###

![20190618120533724.jpg][]

### 默认异步任务线程池 ###

SpringBoot异步任务默认使用的线程池为SimpleAsyncTaskExecutor，其特点如下：

*  默认定义多少异步任务，创建多少线程（创建线程数量太多，占用内存过大，会造成OutOfMemoryError）。
 *  SimpleAsyncTaskExecutor不提供拒绝策略机制。
 *  SimpleAsyncTaskExecutor可通过设置参数concurrencyLimit（值为大于或等于0的整数），指定启用的线程数目；默认concurrencyLimit取值为-1，即不启用资源节流。

### 自定义异步任务线程池 ###

package com.ming.asyncservice;
    
    import org.springframework.aop.interceptor.AsyncUncaughtExceptionHandler;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.scheduling.annotation.AsyncConfigurer;
    import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
    
    import java.util.concurrent.Executor;
    import java.util.concurrent.ThreadPoolExecutor;
    
    @Configuration
    public class AsyncThreadPoolConfig implements AsyncConfigurer { 
    	
    	/** * 自定义线程池 * @return 线程池对象 */
        @Override
        public Executor getAsyncExecutor() { 
            ThreadPoolTaskExecutor threadPoolTaskExecutor = new ThreadPoolTaskExecutor();
            threadPoolTaskExecutor.setCorePoolSize(5);
            threadPoolTaskExecutor.setMaxPoolSize(8);
            threadPoolTaskExecutor.setQueueCapacity(10);
            threadPoolTaskExecutor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy());
            threadPoolTaskExecutor.initialize();
            return threadPoolTaskExecutor;
        }
    	
    	/** * 自定义异常处理器 * @return 异常处理器对象 */
        @Override
        public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() { 
            AsyncUncaughtExceptionHandler syncUncaughtExceptionHandler = (ex, method, params) -> ex.printStackTrace();
            return syncUncaughtExceptionHandler;
        }
    }

### 测试结果 ###

获取异步任务对应的线程名称，线程池从默认的SimpleAsyncTaskExecutor转换成自定义的ThreadPoolTaskExecutor。

![20190618130926979.jpg][]

[20190618120533724.jpg]: /images/20220112/0ca2b85c8dc14bf3b81200bc5791784f.png
[20190618130926979.jpg]: /images/20220112/3e18393e7d6b48f3ae590553c6108746.png