一、异步执行
实现形式二种:
- 应用异步注解 @aysnc、启动类:增加 @EnableAsync 注解
- JDK 8 自身有一个十分好用的 Future 类——CompletableFuture
@AllArgsConstructorpublic class AskThread implements Runnable{ private CompletableFuture<Integer> re = null; public void run() { int myRe = 0; try { myRe = re.get() * re.get(); } catch (Exception e) { e.printStackTrace(); } System.out.println(myRe); } public static void main(String[] args) throws InterruptedException { final CompletableFuture<Integer> future = new CompletableFuture<>(); new Thread(new AskThread(future)).start(); //模仿长时间的计算过程 Thread.sleep(1000); //告知实现后果 future.complete(60); }}
在该示例中,启动一个线程,此时 AskThread 对象还没有拿到它须要的数据,执行到 myRe = re.get() * re.get() 会阻塞。
咱们用休眠 1 秒来模仿一个长时间的计算过程,并将计算结果通知 future 执行后果,AskThread 线程将会继续执行。
public class Calc { public static Integer calc(Integer para) { try { //模仿一个长时间的执行 Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } return para * para; } public static void main(String[] args) throws ExecutionException, InterruptedException { final CompletableFuture<Void> future = CompletableFuture.supplyAsync(() -> calc(50)) .thenApply((i) -> Integer.toString(i)) .thenApply((str) -> "\"" + str + "\"") .thenAccept(System.out::println); future.get(); }}
CompletableFuture.supplyAsync 办法结构一个 CompletableFuture 实例,在 supplyAsync() 办法中,它会在一个新线程中,执行传入的参数。
在这里它会执行 calc() 办法,这个办法可能是比较慢的,但这并不影响 CompletableFuture 实例的结构速度,supplyAsync() 会立刻返回。
而返回的 CompletableFuture 实例就能够作为这次调用的契约,在未来任何场合,用于取得最终的计算结果。
supplyAsync 用于提供返回值的状况,CompletableFuture 还有一个不须要返回值的异步调用办法 runAsync(Runnable runnable),个别咱们在优化 Controller 时,应用这个办法比拟多。
这两个办法如果在不指定线程池的状况下,都是在 ForkJoinPool.common 线程池中执行,而这个线程池中的所有线程都是 Daemon(守护)线程,所以,当主线程完结时,这些线程无论执行结束都会退出零碎。
外围代码:
CompletableFuture.runAsync(() -> this.afterBetProcessor(betRequest,betDetailResult,appUser,id));
异步调用应用 Callable 来实现:
@RestController public class HelloController { private static final Logger logger = LoggerFactory.getLogger(HelloController.class); @Autowired private HelloService hello; @GetMapping("/helloworld") public String helloWorldController() { return hello.sayHello(); } /** * 异步调用restful * 当controller返回值是Callable的时候,springmvc就会启动一个线程将Callable交给TaskExecutor去解决 * 而后DispatcherServlet还有所有的spring拦截器都退出主线程,而后把response放弃关上的状态 * 当Callable执行完结之后,springmvc就会重新启动调配一个request申请,而后DispatcherServlet就从新 * 调用和解决Callable异步执行的返回后果, 而后返回视图 * * @return */ @GetMapping("/hello") public Callable<String> helloController() { logger.info(Thread.currentThread().getName() + " 进入helloController办法"); Callable<String> callable = new Callable<String>() { @Override public String call() throws Exception { logger.info(Thread.currentThread().getName() + " 进入call办法"); String say = hello.sayHello(); logger.info(Thread.currentThread().getName() + " 从helloService办法返回"); return say; } }; logger.info(Thread.currentThread().getName() + " 从helloController办法返回"); return callable; }}
异步调用的形式 WebAsyncTask:
@RestController public class HelloController { private static final Logger logger = LoggerFactory.getLogger(HelloController.class); @Autowired private HelloService hello; /** * 带超时工夫的异步申请 通过WebAsyncTask自定义客户端超工夫 * * @return */ @GetMapping("/world") public WebAsyncTask<String> worldController() { logger.info(Thread.currentThread().getName() + " 进入helloController办法"); // 3s钟没返回,则认为超时 WebAsyncTask<String> webAsyncTask = new WebAsyncTask<>(3000, new Callable<String>() { @Override public String call() throws Exception { logger.info(Thread.currentThread().getName() + " 进入call办法"); String say = hello.sayHello(); logger.info(Thread.currentThread().getName() + " 从helloService办法返回"); return say; } }); logger.info(Thread.currentThread().getName() + " 从helloController办法返回"); webAsyncTask.onCompletion(new Runnable() { @Override public void run() { logger.info(Thread.currentThread().getName() + " 执行结束"); } }); webAsyncTask.onTimeout(new Callable<String>() { @Override public String call() throws Exception { logger.info(Thread.currentThread().getName() + " onTimeout"); // 超时的时候,间接抛异样,让外层对立解决超时异样 throw new TimeoutException("调用超时"); } }); return webAsyncTask; } /** * 异步调用,异样解决,具体的解决流程见MyExceptionHandler类 * * @return */ @GetMapping("/exception") public WebAsyncTask<String> exceptionController() { logger.info(Thread.currentThread().getName() + " 进入helloController办法"); Callable<String> callable = new Callable<String>() { @Override public String call() throws Exception { logger.info(Thread.currentThread().getName() + " 进入call办法"); throw new TimeoutException("调用超时!"); } }; logger.info(Thread.currentThread().getName() + " 从helloController办法返回"); return new WebAsyncTask<>(20000, callable); }}
二、减少内嵌 Tomcat 的最大连接数
代码如下:
@Configurationpublic class TomcatConfig { @Bean public ConfigurableServletWebServerFactory webServerFactory() { TomcatServletWebServerFactory tomcatFactory = new TomcatServletWebServerFactory(); tomcatFactory.addConnectorCustomizers(new MyTomcatConnectorCustomizer()); tomcatFactory.setPort(8005); tomcatFactory.setContextPath("/api-g"); return tomcatFactory; } class MyTomcatConnectorCustomizer implements TomcatConnectorCustomizer { public void customize(Connector connector) { Http11NioProtocol protocol = (Http11NioProtocol) connector.getProtocolHandler(); //设置最大连接数 protocol.setMaxConnections(20000); //设置最大线程数 protocol.setMaxThreads(2000); protocol.setConnectionTimeout(30000); } }}
应用 @ComponentScan()
三、应用 @ComponentScan() 定位扫包
应用 @ComponentScan() 定位扫包比 @SpringBootApplication 扫包更快。
四、默认 Tomcat 容器改为 Undertow
默认 Tomcat 容器改为 Undertow(Jboss 下的服务器,Tomcat 吞吐量 5000,Undertow 吞吐量 8000)
<exclusions> <exclusion> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> </exclusion></exclusions>
改为:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-undertow</artifactId></dependency>
Spring Boot 根底就不介绍了,举荐下这个实战教程:https://github.com/javastacks/spring-boot-best-practice
五、应用 BufferedWriter 进行缓冲
这里不给大家举例,可自行尝试。
六、Deferred 形式实现异步调用
代码如下:
@RestControllerpublic class AsyncDeferredController { private final Logger logger = LoggerFactory.getLogger(this.getClass()); private final LongTimeTask taskService; @Autowired public AsyncDeferredController(LongTimeTask taskService) { this.taskService = taskService; } @GetMapping("/deferred") public DeferredResult<String> executeSlowTask() { logger.info(Thread.currentThread().getName() + "进入executeSlowTask办法"); DeferredResult<String> deferredResult = new DeferredResult<>(); // 调用长时间执行工作 taskService.execute(deferredResult); // 当长时间工作中应用deferred.setResult("world");这个办法时,会从长时间工作中返回,持续controller外面的流程 logger.info(Thread.currentThread().getName() + "从executeSlowTask办法返回"); // 超时的回调办法 deferredResult.onTimeout(new Runnable(){ @Override public void run() { logger.info(Thread.currentThread().getName() + " onTimeout"); // 返回超时信息 deferredResult.setErrorResult("time out!"); } }); // 解决实现的回调办法,无论是超时还是解决胜利,都会进入这个回调办法 deferredResult.onCompletion(new Runnable(){ @Override public void run() { logger.info(Thread.currentThread().getName() + " onCompletion"); } }); return deferredResult; }}
七、异步调用能够应用 AsyncHandlerInterceptor 进行拦挡
代码如下:
@Componentpublic class MyAsyncHandlerInterceptor implements AsyncHandlerInterceptor { private static final Logger logger = LoggerFactory.getLogger(MyAsyncHandlerInterceptor.class); @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {// HandlerMethod handlerMethod = (HandlerMethod) handler; logger.info(Thread.currentThread().getName()+ "服务调用实现,返回后果给客户端"); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { if(null != ex){ System.out.println("产生异样:"+ex.getMessage()); } } @Override public void afterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { // 拦挡之后,从新写回数据,将原来的hello world换成如下字符串 String resp = "my name is chhliu!"; response.setContentLength(resp.length()); response.getOutputStream().write(resp.getBytes()); logger.info(Thread.currentThread().getName() + " 进入afterConcurrentHandlingStarted办法"); }}
参考资料:
- https://my.oschina.net/u/3768341/blog/3001731
- https://blog.csdn.net/liuchuanhong1/article/details/78744138
版权申明:本文为CSDN博主「灬点点」的原创文章,遵循CC 4.0 BY-SA版权协定,转载请附上原文出处链接及本申明。原文链接:https://blog.csdn.net/qq_32447301/article/details/88046026
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