springboot線程池的使用和擴展

實戰環境

windowns10；
jdk1.8；
springboot 1.5.9.RELEASE；
開發工具：IntelliJ IDEA；

實戰源碼

本次實戰的源碼可以在我的GitHub下載，地址：git@github.com:zq2599/blog_demos.git，項目主頁：https://github.com/zq2599/blog_demos

這里面有多個工程，本次用到的工程為threadpooldemoserver，如下圖紅框所示：?
這里寫圖片描述

實戰步驟梳理

本次實戰的步驟如下：?
1. 創建springboot工程；?
2. 創建Service層的接口和實現；?
3. 創建controller，開發一個http服務接口，里面會調用service層的服務；?
4. 創建線程池的配置；?
5. 將Service層的服務異步化，這樣每次調用都會都被提交到線程池異步執行；?
6. 擴展ThreadPoolTaskExecutor，在提交任務到線程池的時候可以觀察到當前線程池的情況；

創建springboot工程

用IntelliJ IDEA創建一個springboot的web工程threadpooldemoserver，pom.xml內容如下：

<?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>

創建Service層的接口和實現

創建一個service層的接口AsyncService，如下：

public interface AsyncService {/*** 執行異步任務*/void executeAsync();
}

對應的AsyncServiceImpl，實現如下：

@Service
public class AsyncServiceImpl implements AsyncService {private static final Logger logger = LoggerFactory.getLogger(AsyncServiceImpl.class);@Overridepublic void executeAsync() {logger.info("start executeAsync");try{Thread.sleep(1000);}catch(Exception e){e.printStackTrace();}logger.info("end executeAsync");}
}

這個方法做的事情很簡單：sleep了一秒鐘；

創建controller

創建一個controller為Hello，里面定義一個http接口，做的事情是調用Service層的服務，如下：

@RestController
public class Hello {private static final Logger logger = LoggerFactory.getLogger(Hello.class);@Autowiredprivate AsyncService asyncService;@RequestMapping("/")public String submit(){logger.info("start submit");//調用service層的任務asyncService.executeAsync();logger.info("end submit");return "success";}
}

至此，我們已經做好了一個http請求的服務，里面做的事情其實是同步的，接下來我們就開始配置springboot的線程池服務，將service層做的事情都提交到線程池中去處理；

springboot的線程池配置

創建一個配置類ExecutorConfig，用來定義如何創建一個ThreadPoolTaskExecutor，要使用@Configuration和@EnableAsync這兩個注解，表示這是個配置類，并且是線程池的配置類，如下所示：

@Configuration
@EnableAsync
public class ExecutorConfig {private static final Logger logger = LoggerFactory.getLogger(ExecutorConfig.class);@Beanpublic Executor asyncServiceExecutor() {logger.info("start asyncServiceExecutor");ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();//配置核心線程數executor.setCorePoolSize(5);//配置最大線程數executor.setMaxPoolSize(5);//配置隊列大小executor.setQueueCapacity(99999);//配置線程池中的線程的名稱前綴executor.setThreadNamePrefix("async-service-");// rejection-policy：當pool已經達到max size的時候，如何處理新任務// CALLER_RUNS：不在新線程中執行任務，而是有調用者所在的線程來執行executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());//執行初始化executor.initialize();return executor;}
}

注意，上面的方法名稱為asyncServiceExecutor，稍后馬上用到；

將Service層的服務異步化

打開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方法進入的線程池是asyncServiceExecutor方法創建的，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");}

驗證效果

將這個springboot運行起來（pom.xml所在文件夾下執行mvn spring-boot:run）；
在瀏覽器輸入：http://localhost:8080；
在瀏覽器用F5按鈕快速多刷新幾次；
在springboot的控制臺看見日志如下：

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，我們可以看到controller的執行線程是”nio-8080-exec-8”，這是tomcat的執行線程，而service層的日志顯示線程名為“async-service-1”，顯然已經在我們配置的線程池中執行了，并且每次請求中，controller的起始和結束日志都是連續打印的，表明每次請求都快速響應了，而耗時的操作都留給線程池中的線程去異步執行；

擴展ThreadPoolTaskExecutor

雖然我們已經用上了線程池，但是還不清楚線程池當時的情況，有多少線程在執行，多少在隊列中等待呢？這里我創建了一個ThreadPoolTaskExecutor的子類，在每次提交線程的時候都會將當前線程池的運行狀況打印出來，代碼如下：

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());}@Overridepublic void execute(Runnable task) {showThreadPoolInfo("1. do execute");super.execute(task);}@Overridepublic void execute(Runnable task, long startTimeout) {showThreadPoolInfo("2. do execute");super.execute(task, startTimeout);}@Overridepublic Future<?> submit(Runnable task) {showThreadPoolInfo("1. do submit");return super.submit(task);}@Overridepublic <T> Future<T> submit(Callable<T> task) {showThreadPoolInfo("2. do submit");return super.submit(task);}@Overridepublic ListenableFuture<?> submitListenable(Runnable task) {showThreadPoolInfo("1. do submitListenable");return super.submitListenable(task);}@Overridepublic <T> ListenableFuture<T> submitListenable(Callable<T> task) {showThreadPoolInfo("2. do submitListenable");return super.submitListenable(task);}
}

如上所示，showThreadPoolInfo方法中將任務總數、已完成數、活躍線程數，隊列大小都打印出來了，然后Override了父類的execute、submit等方法，在里面調用showThreadPoolInfo方法，這樣每次有任務被提交到線程池的時候，都會將當前線程池的基本情況打印到日志中；

修改ExecutorConfig.java的asyncServiceExecutor方法，將ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor()改為ThreadPoolTaskExecutor executor = new VisiableThreadPoolTaskExecutor()，如下所示：

@Beanpublic Executor asyncServiceExecutor() {logger.info("start asyncServiceExecutor");//使用VisiableThreadPoolTaskExecutorThreadPoolTaskExecutor executor = new VisiableThreadPoolTaskExecutor();//配置核心線程數executor.setCorePoolSize(5);//配置最大線程數executor.setMaxPoolSize(5);//配置隊列大小executor.setQueueCapacity(99999);//配置線程池中的線程的名稱前綴executor.setThreadNamePrefix("async-service-");// rejection-policy：當pool已經達到max size的時候，如何處理新任務// CALLER_RUNS：不在新線程中執行任務，而是有調用者所在的線程來執行executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());//執行初始化executor.initialize();return executor;}

再次啟動該工程，再瀏覽器反復刷新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

注意這一行日志：2. do submit,taskCount [101], completedTaskCount [87], activeCount [5], queueSize [9]

這說明提交任務到線程池的時候，調用的是submit(Callable task)這個方法，當前已經提交了101個任務，完成了87個，當前有5個線程在處理任務，還剩9個任務在隊列中等待，線程池的基本情況一路了然；

至此，springboot線程池服務的實戰就完成了，希望能幫您在工程中快速實現異步服務；

spring-boot 方法異步調用，自定義線程池配置使用

1、在主類中添加@EnableAsync注解：

@SpringBootApplication
@EnableScheduling
@EnableAsync
public class MySpringBootApplication {private static Logger logger = LoggerFactory.getLogger(MySpringBootApplication.class);public static void main(String[] args) {SpringApplication.run(MySpringBootApplication.class, args);logger.info("My Spring Boot Application Started");}

2、創建一個AsyncTask類，在里面添加兩個用@Async注解的task：

@Component
public class AsyncTask {protected final Logger logger = LoggerFactory.getLogger(this.getClass());@Asyncpublic Future<String> doTask1() throws InterruptedException{logger.info("Task1 started.");long start = System.currentTimeMillis();Thread.sleep(5000);long end = System.currentTimeMillis();logger.info("Task1 finished, time elapsed: {} ms.", end-start);return new AsyncResult<>("Task1 accomplished!");}@Asyncpublic Future<String> doTask2() throws InterruptedException{logger.info("Task2 started.");long start = System.currentTimeMillis();Thread.sleep(3000);long end = System.currentTimeMillis();logger.info("Task2 finished, time elapsed: {} ms.", end-start);return new AsyncResult<>("Task2 accomplished!");}
}

3、萬事俱備，開始測試：


public class TaskTests extends BasicUtClass{@Autowiredprivate AsyncTask asyncTask;@Testpublic void AsyncTaskTest() throws InterruptedException, ExecutionException {Future<String> task1 = asyncTask.doTask1();Future<String> task2 = asyncTask.doTask2();while(true) {if(task1.isDone() && task2.isDone()) {logger.info("Task1 result: {}", task1.get());logger.info("Task2 result: {}", task2.get());break;}Thread.sleep(1000);}logger.info("All tasks finished.");}
}

測試結果：

2016-12-13 11:12:24,850:INFO main (AsyncExecutionAspectSupport.java:245) - No TaskExecutor bean found for async processing
2016-12-13 11:12:24,864:INFO SimpleAsyncTaskExecutor-1 (AsyncTask.java:22) - Task1 started.
2016-12-13 11:12:24,865:INFO SimpleAsyncTaskExecutor-2 (AsyncTask.java:34) - Task2 started.
2016-12-13 11:12:27,869:INFO SimpleAsyncTaskExecutor-2 (AsyncTask.java:39) - Task2 finished, time elapsed: 3001 ms.
2016-12-13 11:12:29,866:INFO SimpleAsyncTaskExecutor-1 (AsyncTask.java:27) - Task1 finished, time elapsed: 5001 ms.
2016-12-13 11:12:30,853:INFO main (TaskTests.java:23) - Task1 result: Task1 accomplished!
2016-12-13 11:12:30,853:INFO main (TaskTests.java:24) - Task2 result: Task2 accomplished!
2016-12-13 11:12:30,854:INFO main (TaskTests.java:30) - All tasks finished.

可以看到，沒有自定義的Executor，所以使用缺省的TaskExecutor 。

前面是最簡單的使用方法。如果想使用自定義的Executor，可以按照如下幾步來：

1、新建一個Executor配置類，順便把@EnableAsync注解搬到這里來：

@Configuration
@EnableAsync
public class ExecutorConfig {/** Set the ThreadPoolExecutor's core pool size. */private int corePoolSize = 10;/** Set the ThreadPoolExecutor's maximum pool size. */private int maxPoolSize = 200;/** Set the capacity for the ThreadPoolExecutor's BlockingQueue. */private int queueCapacity = 10;@Beanpublic Executor mySimpleAsync() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setCorePoolSize(corePoolSize);executor.setMaxPoolSize(maxPoolSize);executor.setQueueCapacity(queueCapacity);executor.setThreadNamePrefix("MySimpleExecutor-");executor.initialize();return executor;}@Beanpublic Executor myAsync() {ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();executor.setCorePoolSize(corePoolSize);executor.setMaxPoolSize(maxPoolSize);executor.setQueueCapacity(queueCapacity);executor.setThreadNamePrefix("MyExecutor-");// rejection-policy：當pool已經達到max size的時候，如何處理新任務// CALLER_RUNS：不在新線程中執行任務，而是有調用者所在的線程來執行executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());executor.initialize();return executor;}
}

這里定義了兩個不同的Executor，第二個重新設置了pool已經達到max size時候的處理方法；同時指定了線程名字的前綴。

2、自定義Executor的使用：

@Component
public class AsyncTask {protected final Logger logger = LoggerFactory.getLogger(this.getClass());@Async("mySimpleAsync")public Future<String> doTask1() throws InterruptedException{logger.info("Task1 started.");long start = System.currentTimeMillis();Thread.sleep(5000);long end = System.currentTimeMillis();logger.info("Task1 finished, time elapsed: {} ms.", end-start);return new AsyncResult<>("Task1 accomplished!");}@Async("myAsync")public Future<String> doTask2() throws InterruptedException{logger.info("Task2 started.");long start = System.currentTimeMillis();Thread.sleep(3000);long end = System.currentTimeMillis();logger.info("Task2 finished, time elapsed: {} ms.", end-start);return new AsyncResult<>("Task2 accomplished!");}
}

就是把上面自定義Executor的類名，放進@Async注解中。

3、（測試用例不變）測試結果：

2016-12-13 10:57:11,998:INFO MySimpleExecutor-1 (AsyncTask.java:22) - Task1 started.
2016-12-13 10:57:12,001:INFO MyExecutor-1 (AsyncTask.java:34) - Task2 started.
2016-12-13 10:57:15,007:INFO MyExecutor-1 (AsyncTask.java:39) - Task2 finished, time elapsed: 3000 ms.
2016-12-13 10:57:16,999:INFO MySimpleExecutor-1 (AsyncTask.java:27) - Task1 finished, time elapsed: 5001 ms.
2016-12-13 10:57:17,994:INFO main (TaskTests.java:23) - Task1 result: Task1 accomplished!
2016-12-13 10:57:17,994:INFO main (TaskTests.java:24) - Task2 result: Task2 accomplished!
2016-12-13 10:57:17,994:INFO main (TaskTests.java:30) - All tasks finished.
2016-12-13 10:57:18,064 Thread-3 WARN Unable to register Log4j shutdown hook because JVM is shutting down. Using SimpleLogger

可見，線程名字的前綴變了，兩個task使用了不同的線程池了。