我们常用ThreadPoolExecutor提供的线程池服务,springboot框架提供了@Async注解,帮助我们更方便的将业务逻辑提交到线程池中异步执行,今天我们就来实战体验这个线程池服务;

本文地址:http://blog.csdn.net/boling_cavalry/article/details/79120268
<http://blog.csdn.net/boling_cavalry/article/details/79120268>

实战环境

* windowns10;
* jdk1.8;
* springboot 1.5.9.RELEASE;
* 开发工具:IntelliJ IDEA;
实战源码

本次实战的源码可以在我的GitHub下载,地址:[email protected]:zq2599/blog_demos.git,项目主页:
https://github.com/zq2599/blog_demos <https://github.com/zq2599/blog_demos>

这里面有多个工程,本次用到的工程为threadpooldemoserver,如下图红框所示:


实战步骤梳理

本次实战的步骤如下:
1. 创建springboot工程;
2. 创建Service层的接口和实现;
3. 创建controller,开发一个http服务接口,里面会调用service层的服务;
4. 创建线程池的配置;
5. 将Service层的服务异步化,这样每次调用都会都被提交到线程池异步执行;
6. 扩展ThreadPoolTaskExecutor,在提交任务到线程池的时候可以观察到当前线程池的情况;

创建springboot工程

用IntelliJ IDEA创建一个springboot的web工程threadpooldemoserver,pom.xml内容如下:
<?xml version="1.0" encoding="UTF-8"?> <project xmlns=
"http://maven.apache.org/POM/4.0.0" xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=
"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion> <groupId>com.bolingcavalry</groupId> <
artifactId>threadpooldemoserver</artifactId> <version>0.0.1-SNAPSHOT</version> <
packaging>jar</packaging> <name>threadpooldemoserver</name> <description>Demo
project for Spring Boot</description> <parent> <groupId>org.springframework.boot
</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>
1.5.9.RELEASE</version> <relativePath/> <!-- lookup parent from repository -->
</parent> <properties> <project.build.sourceEncoding>UTF-8</
project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</
project.reporting.outputEncoding> <java.version>1.8</java.version> </properties>
<dependencies> <dependency> <groupId>org.springframework.boot</groupId> <
artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <
build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <
artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build>
</project>
创建Service层的接口和实现

创建一个service层的接口AsyncService,如下:
public interface AsyncService { /** * 执行异步任务 */ void executeAsync(); }
对应的AsyncServiceImpl,实现如下:
@Service public class AsyncServiceImpl implements AsyncService { private static
final Logger logger = LoggerFactory.getLogger(AsyncServiceImpl.class); @Override
public void executeAsync() { logger.info("start executeAsync"); try{
Thread.sleep(1000); }catch(Exception e){ e.printStackTrace(); } logger.info(
"end executeAsync"); } }
这个方法做的事情很简单:sleep了一秒钟;

创建controller

创建一个controller为Hello,里面定义一个http接口,做的事情是调用Service层的服务,如下:
@RestController public class Hello { private static final Logger logger =
LoggerFactory.getLogger(Hello.class);@Autowired private AsyncService
asyncService;@RequestMapping("/") public String submit(){ logger.info("start
submit"); //调用service层的任务 asyncService.executeAsync(); logger.info("end submit"
);return "success"; } }

至此,我们已经做好了一个http请求的服务,里面做的事情其实是同步的,接下来我们就开始配置springboot的线程池服务,将service层做的事情都提交到线程池中去处理;

springboot的线程池配置


创建一个配置类ExecutorConfig,用来定义如何创建一个ThreadPoolTaskExecutor,要使用@Configuration和@EnableAsync这两个注解,表示这是个配置类,并且是线程池的配置类,如下所示:
@Configuration @EnableAsync public class ExecutorConfig { private static final
Logger logger = LoggerFactory.getLogger(ExecutorConfig.class);@Bean public
ExecutorasyncServiceExecutor() { logger.info("start asyncServiceExecutor");
ThreadPoolTaskExecutor executor =new ThreadPoolTaskExecutor(); //配置核心线程数
executor.setCorePoolSize(5); //配置最大线程数 executor.setMaxPoolSize(5); //配置队列大小
executor.setQueueCapacity(99999); //配置线程池中的线程的名称前缀 executor.setThreadNamePrefix(
"async-service-"); // rejection-policy:当pool已经达到max size的时候,如何处理新任务 //
CALLER_RUNS:不在新线程中执行任务,而是有调用者所在的线程来执行 executor.setRejectedExecutionHandler(new
ThreadPoolExecutor.CallerRunsPolicy());//执行初始化 executor.initialize(); return
executor; } }
注意,上面的方法名称为asyncServiceExecutor,稍后马上用到;

将Service层的服务异步化

打开AsyncServiceImpl.java,在executeAsync方法上增加注解@Async(“asyncServiceExecutor”)
,asyncServiceExecutor是前面ExecutorConfig.java中的方法名,表明executeAsync方法进入的线程池是asyncServiceExecutor方法创建的,如下:
@Override @Async("asyncServiceExecutor") public void executeAsync() {
logger.info("start executeAsync"); try{ Thread.sleep(1000); }catch(Exception
e){ e.printStackTrace(); } logger.info("end executeAsync"); }
验证效果

* 将这个springboot运行起来(pom.xml所在文件夹下执行mvn spring-boot:run);
* 在浏览器输入:http://localhost:8080 <http://localhost:8080>;
* 在浏览器用F5按钮快速多刷新几次;
* 在springboot的控制台看见日志如下: 2018-01-21 22:43:18.630 INFO 14824 --- [nio-8080
-exec-8] c.b.t.controller.Hello : start submit 2018-01-21 22:43:18.630 INFO
14824 --- [nio-8080-exec-8] c.b.t.controller.Hello : end submit 2018-01-21 22:43
:18.929 INFO 14824 --- [async-service-1] c.b.t.service.impl.AsyncServiceImpl :
end executeAsync2018-01-21 22:43:18.930 INFO 14824 --- [async-service-1] c.b.t
.service.impl.AsyncServiceImpl : start executeAsync 2018-01-21 22:43:19.005 INFO
14824 --- [async-service-2] c.b.t.service.impl.AsyncServiceImpl : end
executeAsync2018-01-21 22:43:19.006 INFO 14824 --- [async-service-2] c.b.t
.service.impl.AsyncServiceImpl : start executeAsync 2018-01-21 22:43:19.175 INFO
14824 --- [async-service-3] c.b.t.service.impl.AsyncServiceImpl : end
executeAsync2018-01-21 22:43:19.175 INFO 14824 --- [async-service-3] c.b.t
.service.impl.AsyncServiceImpl : start executeAsync 2018-01-21 22:43:19.326 INFO
14824 --- [async-service-4] c.b.t.service.impl.AsyncServiceImpl : end
executeAsync2018-01-21 22:43:19.495 INFO 14824 --- [async-service-5] c.b.t
.service.impl.AsyncServiceImpl : end executeAsync 2018-01-21 22:43:19.930 INFO
14824 --- [async-service-1] c.b.t.service.impl.AsyncServiceImpl : end
executeAsync2018-01-21 22:43:20.006 INFO 14824 --- [async-service-2] c.b.t
.service.impl.AsyncServiceImpl : end executeAsync 2018-01-21 22:43:20.191 INFO
14824 --- [async-service-3] c.b.t.service.impl.AsyncServiceImpl : end
executeAsync

如上日志所示,我们可以看到controller的执行线程是”nio-8080-exec-8”,这是tomcat的执行线程,而service层的日志显示线程名为“async-service-1”,显然已经在我们配置的线程池中执行了,并且每次请求中,controller的起始和结束日志都是连续打印的,表明每次请求都快速响应了,而耗时的操作都留给线程池中的线程去异步执行;

扩展ThreadPoolTaskExecutor


虽然我们已经用上了线程池,但是还不清楚线程池当时的情况,有多少线程在执行,多少在队列中等待呢?这里我创建了一个ThreadPoolTaskExecutor的子类,在每次提交线程的时候都会将当前线程池的运行状况打印出来,代码如下:
public class VisiableThreadPoolTaskExecutor extends ThreadPoolTaskExecutor {
private static final Logger logger =
LoggerFactory.getLogger(VisiableThreadPoolTaskExecutor.class);private void
showThreadPoolInfo(String prefix){ ThreadPoolExecutor threadPoolExecutor =
getThreadPoolExecutor();if(null==threadPoolExecutor){ return; } logger.info(
"{}, {},taskCount [{}], completedTaskCount [{}], activeCount [{}], queueSize
[{}]", this.getThreadNamePrefix(), prefix, threadPoolExecutor.getTaskCount(),
threadPoolExecutor.getCompletedTaskCount(),
threadPoolExecutor.getActiveCount(), threadPoolExecutor.getQueue().size()); }
@Override public void execute(Runnable task) { showThreadPoolInfo("1. do
execute"); super.execute(task); } @Override public void execute(Runnable task,
long startTimeout) { showThreadPoolInfo("2. do execute"); super.execute(task,
startTimeout); }@Override public Future<?> submit(Runnable task) {
showThreadPoolInfo("1. do submit"); return super.submit(task); } @Override
public <T> Future<T> submit(Callable<T> task) { showThreadPoolInfo("2. do
submit"); return super.submit(task); } @Override public ListenableFuture<?>
submitListenable(Runnable task) { showThreadPoolInfo("1. do submitListenable");
return super.submitListenable(task); } @Override public <T> ListenableFuture<T>
submitListenable(Callable<T> task) { showThreadPoolInfo("2. do submitListenable"
);return super.submitListenable(task); } }

如上所示,showThreadPoolInfo方法中将任务总数、已完成数、活跃线程数,队列大小都打印出来了,然后Override了父类的execute、submit等方法,在里面调用showThreadPoolInfo方法,这样每次有任务被提交到线程池的时候,都会将当前线程池的基本情况打印到日志中;

修改ExecutorConfig.java的asyncServiceExecutor方法,将ThreadPoolTaskExecutor executor
= new ThreadPoolTaskExecutor()改为ThreadPoolTaskExecutor executor = new
VisiableThreadPoolTaskExecutor(),如下所示:
@Bean public Executor asyncServiceExecutor() { logger.info("start
asyncServiceExecutor"); //使用VisiableThreadPoolTaskExecutor
ThreadPoolTaskExecutor executor =new VisiableThreadPoolTaskExecutor(); //配置核心线程数
executor.setCorePoolSize(5); //配置最大线程数 executor.setMaxPoolSize(5); //配置队列大小
executor.setQueueCapacity(99999); //配置线程池中的线程的名称前缀 executor.setThreadNamePrefix(
"async-service-"); // rejection-policy:当pool已经达到max size的时候,如何处理新任务 //
CALLER_RUNS:不在新线程中执行任务,而是有调用者所在的线程来执行 executor.setRejectedExecutionHandler(new
ThreadPoolExecutor.CallerRunsPolicy());//执行初始化 executor.initialize(); return
executor; }
再次启动该工程,再浏览器反复刷新http://localhost:8080 <http://localhost:8080>,看到的日志如下:
2018-01-21 23:04:56.113 INFO 15580 --- [nio-8080-exec-1] c.b.t.e
.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [99],
completedTaskCount [85], activeCount [5], queueSize [9] 2018-01-21 23:04:56.113
INFO15580 --- [nio-8080-exec-1] c.b.t.controller.Hello : end submit 2018-01-21
23:04:56.225 INFO 15580 --- [async-service-1] c.b.t.service.impl
.AsyncServiceImpl : end executeAsync 2018-01-21 23:04:56.225 INFO 15580 ---
[async-service-1] c.b.t.service.impl.AsyncServiceImpl : start executeAsync 2018-
01-21 23:04:56.240 INFO 15580 --- [nio-8080-exec-2] c.b.t.controller.Hello :
start submit2018-01-21 23:04:56.240 INFO 15580 --- [nio-8080-exec-2] c.b.t.e
.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [100],
completedTaskCount [86], activeCount [5], queueSize [9] 2018-01-21 23:04:56.240
INFO15580 --- [nio-8080-exec-2] c.b.t.controller.Hello : end submit 2018-01-21
23:04:56.298 INFO 15580 --- [async-service-2] c.b.t.service.impl
.AsyncServiceImpl : end executeAsync 2018-01-21 23:04:56.298 INFO 15580 ---
[async-service-2] c.b.t.service.impl.AsyncServiceImpl : start executeAsync 2018-
01-21 23:04:56.372 INFO 15580 --- [nio-8080-exec-3] c.b.t.controller.Hello :
start submit2018-01-21 23:04:56.373 INFO 15580 --- [nio-8080-exec-3] c.b.t.e
.VisiableThreadPoolTaskExecutor : async-service-, 2. do submit,taskCount [101],
completedTaskCount [87], activeCount [5], queueSize [9] 2018-01-21 23:04:56.373
INFO15580 --- [nio-8080-exec-3] c.b.t.controller.Hello : end submit 2018-01-21
23:04:56.444 INFO 15580 --- [async-service-3] c.b.t.service.impl
.AsyncServiceImpl : end executeAsync 2018-01-21 23:04:56.445 INFO 15580 ---
[async-service-3] c.b.t.service.impl.AsyncServiceImpl : start executeAsync
注意这一行日志:2. do submit,taskCount [101], completedTaskCount [87], activeCount
[5], queueSize [9]

这说明提交任务到线程池的时候,调用的是submit(Callable task)
这个方法,当前已经提交了101个任务,完成了87个,当前有5个线程在处理任务,还剩9个任务在队列中等待,线程池的基本情况一路了然;

至此,springboot线程池服务的实战就完成了,希望能帮您在工程中快速实现异步服务;