并发编程 线程池以及@Async注解的使用

华为云博客 技术博客 22450 10

建议先看我另外一篇文章：并发编程使用了 线程池 ThreadPoolExecutor 程序性能有了质的突破

开发环境
  • SpringBoot 2.1.10.RELEASE
  • JDK 1.8
1：启动类添加@EnableAsync注解
package com.nobody;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;

@SpringBootApplication
@EnableAsync
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}

}
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2：线程池配置
package com.nobody.config;

import java.util.concurrent.Executor;
import java.util.concurrent.ThreadPoolExecutor;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

@Configuration
public class ExecutorConfig { public static final int CORE_POOL_SIZE = 5; public static final int MAX_POOL_SIZE = 10; public static final int QUEUE_CAPACITY = 100; @Bean("myExecutor") public Executor asyncServiceExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); // 核心线程数大小 executor.setCorePoolSize(CORE_POOL_SIZE); // 最大线程数大小 executor.setMaxPoolSize(MAX_POOL_SIZE); // 阻塞队列容量 executor.setQueueCapacity(QUEUE_CAPACITY); // 线程名前缀 executor.setThreadNamePrefix("myTask-"); // rejectionPolicy：当queue达到maxSize并且此时maxPoolSize也达到最大值的时候，对于新任务的处理策略 // CallerRunsPolicy：不在新线程中执行任务，而是交由调用者所在的线程来执行 executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy()); executor.initialize(); return executor; }
}
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3：编写异步方法
package com.nobody.domain;

import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.AsyncResult;
import org.springframework.stereotype.Service;

@Service
public class AsyncService { private static final Logger LOGGER = LoggerFactory.getLogger(AsyncService.class); // 简单版本 @Async public void asyncTaskA() { LOGGER.info("asyncTaskA 异步方法执行."); } // 入参类型，此处将调用者(线程)的MDC信息传入，主要是保持日志输出时，两个线程有同样的traceId @Async public void asyncTaslB(Map<String, String> contextMap) { MDC.setContextMap(contextMap); LOGGER.info("asyncTaskB 异步方法执行."); } // 线程执行后计数器减1 @Async public void asyncTaskC(CountDownLatch cdl) { LOGGER.info("asyncTaskC 异步方法执行."); try { TimeUnit.SECONDS.sleep(2); } catch (InterruptedException e) { e.printStackTrace(); } cdl.countDown(); } // 有返回参数类型 @Async public Future<String> asyncTaskD(String message) { LOGGER.info("asyncTaskD 异步方法执行."); return new AsyncResult<String>("@" + message); }

}
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4：异步调用
package com.nobody.controller;

import java.util.concurrent.ExecutionException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.nobody.domain.AsyncService;

@RestController
@RequestMapping("demo")
public class DemoController { private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class); @Autowired private AsyncService asyncService; @GetMapping("test") public void test() throws InterruptedException, ExecutionException { asyncService.asyncTaskA(); LOGGER.info("主线程执行..."); }

}
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输出结果：
在这里插入图片描述

package com.nobody.controller;

import java.util.UUID;
import java.util.concurrent.ExecutionException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.nobody.domain.AsyncService;

@RestController
@RequestMapping("demo")
public class DemoController { private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class); @Autowired private AsyncService asyncService; @GetMapping("test") public void test() throws InterruptedException, ExecutionException { MDC.put("traceId", UUID.randomUUID().toString().replaceFirst("-", "")); asyncService.asyncTaskB(MDC.getCopyOfContextMap()); LOGGER.info("主线程执行..."); }

}
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输出结果：
在这里插入图片描述

package com.nobody.controller;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.nobody.domain.AsyncService;

@RestController
@RequestMapping("demo")
public class DemoController { private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class); @Autowired private AsyncService asyncService; @GetMapping("test") public void test() throws InterruptedException, ExecutionException { CountDownLatch cdl = new CountDownLatch(2); asyncService.asyncTaskC(cdl); asyncService.asyncTaskC(cdl); try { // 等等两个线程执行后，再继续下面的执行，如果超过5s则不等待 cdl.await(5, TimeUnit.SECONDS); } catch (InterruptedException e) { e.printStackTrace(); } LOGGER.info("主线程执行..."); }

}
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输出结果：
在这里插入图片描述

package com.nobody.controller;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.nobody.domain.AsyncService;

@RestController
@RequestMapping("demo")
public class DemoController { private static final Logger LOGGER = LoggerFactory.getLogger(DemoController.class); @Autowired private AsyncService asyncService; @GetMapping("test") public void test() throws InterruptedException, ExecutionException { Future<String> future = asyncService.asyncTaskD("Mr.nobody"); LOGGER.info("future result:" + future.get()); LOGGER.info("主线程执行..."); }

}
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在这里插入图片描述

文章来源: javalib.blog.csdn.net，作者：陈皮的JavaLib，版权归原作者所有，如需转载，请联系作者。

原文链接：javalib.blog.csdn.net/article/details/106280373

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