springboot线程池关闭

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您好,Spring Boot中的线程池可以通过调用ThreadPoolTaskExecutor的shutdown()方法来关闭。shutdown()方法会等待正在执行的任务完成,然后关闭线程池,如果您想立即关闭线程池,可以调用shutdownNow()方法。shutdownNow()方法会立即关闭线程池,不管正在执行的任务是否完成。此外,您还可以使用awaitTermination()方法来等待线程池中的任务完成,然后再关闭线程池。 参考技术A Springboot线程池关闭是指springboot程序在关闭时,会关闭线程池,这样的话,程序中的所有线程都会被关闭,从而确保系统的安全性。线程池关闭也可以避免程序占用过多的资源,减少系统的维护成本。

Springboot线程池服务实战分享

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;
实战环境
windowns10;
jdk1.8;
springboot 1.5.9.RELEASE;
开发工具:IntelliJ IDEA;

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:
创建springboot工程;
创建Service层的接口和实现;
创建controller,开发一个http服务接口,里面会调用service层的服务;
创建线程池的配置;
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;
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 Executor asyncServiceExecutor() 
        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
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 executeAsync
2018-01-21 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 executeAsync
2018-01-21 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 executeAsync
2018-01-21 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 executeAsync
2018-01-21 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 executeAsync
2018-01-21 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,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  INFO 15580 --- [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 submit
2018-01-21 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  INFO 15580 --- [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 submit
2018-01-21 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  INFO 15580 --- [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。

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