7種方式，教你提升 SpringBoot 項目的吞吐量

一、異步執(zhí)行

實現(xiàn)方式二種：

1. 使用異步注解@aysnc、啟動類：添加@EnableAsync注解
2. JDK 8本身有一個非常好用的Future類——CompletableFuture

@AllArgsConstructor
public?class?AskThread?implements?Runnable{
????private?CompletableFuture?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?future?=?new?CompletableFuture<>();
????????new?Thread(new?AskThread(future)).start();
????????//模擬長時間的計算過程
????????Thread.sleep(1000);
????????//告知完成結果
????????future.complete(60);
????}
}

在該示例中，啟動一個線程，此時AskThread對象還沒有拿到它需要的數(shù)據(jù)，執(zhí)行到 myRe = re.get() * re.get()會阻塞。我們用休眠1秒來模擬一個長時間的計算過程，并將計算結果告訴future執(zhí)行結果，AskThread線程將會繼續(xù)執(zhí)行。

public?class?Calc?{
????public?static?Integer?calc(Integer?para)?{
????????try?{
????????????//模擬一個長時間的執(zhí)行
????????????Thread.sleep(1000);
????????}?catch?(InterruptedException?e)?{
????????????e.printStackTrace();
????????}
????????return?para?*?para;
????}

????public?static?void?main(String[]?args)?throws?ExecutionException,?InterruptedException?{
????????final?CompletableFuture?future?=?CompletableFuture.supplyAsync(()?->?calc(50))
????????????????.thenApply((i)?->?Integer.toString(i))
????????????????.thenApply((str)?->?"\""?+?str?+?"\"")
????????????????.thenAccept(System.out::println);
????????future.get();
????}
}

CompletableFuture.supplyAsync方法構造一個CompletableFuture實例，在supplyAsync()方法中，它會在一個新線程中，執(zhí)行傳入的參數(shù)。在這里它會執(zhí)行calc()方法，這個方法可能是比較慢的，但這并不影響CompletableFuture實例的構造速度，supplyAsync()會立即返回。而返回的CompletableFuture實例就可以作為這次調用的契約，在將來任何場合，用于獲得最終的計算結果。

supplyAsync用于提供返回值的情況，CompletableFuture還有一個不需要返回值的異步調用方法runAsync(Runnable runnable),一般我們在優(yōu)化Controller時，使用這個方法比較多。這兩個方法如果在不指定線程池的情況下，都是在ForkJoinPool.common線程池中執(zhí)行，而這個線程池中的所有線程都是Daemon（守護）線程，所以，當主線程結束時，這些線程無論執(zhí)行完畢都會退出系統(tǒng)。

核心代碼：

CompletableFuture.runAsync(()?->
???this.afterBetProcessor(betRequest,betDetailResult,appUser,id)
);

異步調用使用Callable來實現(xiàn)

@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();??
????}??
??
????/**?
?????*?異步調用restful?
?????*?當controller返回值是Callable的時候，springmvc就會啟動一個線程將Callable交給TaskExecutor去處理?
?????*?然后DispatcherServlet還有所有的spring攔截器都退出主線程，然后把response保持打開的狀態(tài)?
?????*?當Callable執(zhí)行結束之后，springmvc就會重新啟動分配一個request請求，然后DispatcherServlet就重新?
?????*?調用和處理Callable異步執(zhí)行的返回結果，?然后返回視圖?
?????*??
?????*?@return?
?????*/??
????@GetMapping("/hello")??
????public?Callable?helloController()?{??
????????logger.info(Thread.currentThread().getName()?+?"?進入helloController方法");??
????????Callable?callable?=?new?Callable()?{??
??
????????????@Override??
????????????public?String?call()?throws?Exception?{??
????????????????logger.info(Thread.currentThread().getName()?+?"?進入call方法");??
????????????????String?say?=?hello.sayHello();??
????????????????logger.info(Thread.currentThread().getName()?+?"?從helloService方法返回");??
????????????????return?say;??
????????????}??
????????};??
????????logger.info(Thread.currentThread().getName()?+?"?從helloController方法返回");??
????????return?callable;??
????}??
}??

異步調用的方式 WebAsyncTask

@RestController??
public?class?HelloController?{??
??
????private?static?final?Logger?logger?=?LoggerFactory.getLogger(HelloController.class);??
??????
????@Autowired??
????private?HelloService?hello;??
??
????????/**?
?????*?帶超時時間的異步請求?通過WebAsyncTask自定義客戶端超時間?
?????*??
?????*?@return?
?????*/??
????@GetMapping("/world")??
????public?WebAsyncTask?worldController()?{??
????????logger.info(Thread.currentThread().getName()?+?"?進入helloController方法");??
??
????????//?3s鐘沒返回，則認為超時??
????????WebAsyncTask?webAsyncTask?=?new?WebAsyncTask<>(3000,?new?Callable()?{??
??
????????????@Override??
????????????public?String?call()?throws?Exception?{??
????????????????logger.info(Thread.currentThread().getName()?+?"?進入call方法");??
????????????????String?say?=?hello.sayHello();??
????????????????logger.info(Thread.currentThread().getName()?+?"?從helloService方法返回");??
????????????????return?say;??
????????????}??
????????});??
????????logger.info(Thread.currentThread().getName()?+?"?從helloController方法返回");??
??
????????webAsyncTask.onCompletion(new?Runnable()?{??
??
????????????@Override??
????????????public?void?run()?{??
????????????????logger.info(Thread.currentThread().getName()?+?"?執(zhí)行完畢");??
????????????}??
????????});??
??
????????webAsyncTask.onTimeout(new?Callable()?{??
??
????????????@Override??
????????????public?String?call()?throws?Exception?{??
????????????????logger.info(Thread.currentThread().getName()?+?"?onTimeout");??
????????????????//?超時的時候，直接拋異常，讓外層統(tǒng)一處理超時異常??
????????????????throw?new?TimeoutException("調用超時");??
????????????}??
????????});??
????????return?webAsyncTask;??
????}??
??
????/**?
?????*?異步調用，異常處理，詳細的處理流程見MyExceptionHandler類?
?????*??
?????*?@return?
?????*/??
????@GetMapping("/exception")??
????public?WebAsyncTask?exceptionController()?{??
????????logger.info(Thread.currentThread().getName()?+?"?進入helloController方法");??
????????Callable?callable?=?new?Callable()?{??
??
????????????@Override??
????????????public?String?call()?throws?Exception?{??
????????????????logger.info(Thread.currentThread().getName()?+?"?進入call方法");??
????????????????throw?new?TimeoutException("調用超時!");??
????????????}??
????????};??
????????logger.info(Thread.currentThread().getName()?+?"?從helloController方法返回");??
????????return?new?WebAsyncTask<>(20000,?callable);??
????}??
??
}??

二、增加內嵌Tomcat的最大連接數(shù)

@Configuration
public?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();
????????????//設置最大連接數(shù)???????????????
????????????protocol.setMaxConnections(20000);
????????????//設置最大線程數(shù)???????????????
????????????protocol.setMaxThreads(2000);
????????????protocol.setConnectionTimeout(30000);
????????}
????}

}

三、使用@ComponentScan()定位掃包比@SpringBootApplication掃包更快

四、默認tomcat容器改為Undertow（Jboss下的服務器，Tomcat吞吐量5000，Undertow吞吐量8000）

<exclusions>
??<exclusion>
?????<groupId>org.springframework.bootgroupId>
?????<artifactId>spring-boot-starter-tomcatartifactId>
??exclusion>
exclusions>

改為:

<dependency>
??<groupId>org.springframework.bootgroupId>
??<artifactId>spring-boot-starter-undertowartifactId>
dependency>

五、使用 BufferedWriter 進行緩沖

六、Deferred方式實現(xiàn)異步調用

@RestController
public?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?executeSlowTask()?{
????????logger.info(Thread.currentThread().getName()?+?"進入executeSlowTask方法");
????????DeferredResult?deferredResult?=?new?DeferredResult<>();
????????//?調用長時間執(zhí)行任務
????????taskService.execute(deferredResult);
????????//?當長時間任務中使用deferred.setResult("world");這個方法時，會從長時間任務中返回，繼續(xù)controller里面的流程
????????logger.info(Thread.currentThread().getName()?+?"從executeSlowTask方法返回");
????????//?超時的回調方法
????????deferredResult.onTimeout(new?Runnable(){
??
???@Override
???public?void?run()?{
????logger.info(Thread.currentThread().getName()?+?"?onTimeout");
????//?返回超時信息
????deferredResult.setErrorResult("time?out!");
???}
??});
????????
????????//?處理完成的回調方法，無論是超時還是處理成功，都會進入這個回調方法
????????deferredResult.onCompletion(new?Runnable(){
??
???@Override
???public?void?run()?{
????logger.info(Thread.currentThread().getName()?+?"?onCompletion");
???}
??});
????????
????????return?deferredResult;
????}
}

七、異步調用可以使用AsyncHandlerInterceptor進行攔截

@Component
public?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()+?"服務調用完成，返回結果給客戶端");
?}
?
?@Override
?public?void?afterCompletion(HttpServletRequest?request,?HttpServletResponse?response,?Object?handler,?Exception?ex)
???throws?Exception?{
??if(null?!=?ex){
???System.out.println("發(fā)生異常:"+ex.getMessage());
??}
?}
?
?@Override
?public?void?afterConcurrentHandlingStarted(HttpServletRequest?request,?HttpServletResponse?response,?Object?handler)
???throws?Exception?{
??
??//?攔截之后，重新寫回數(shù)據(jù)，將原來的hello?world換成如下字符串
??String?resp?=?"my?name?is?chhliu!";
??response.setContentLength(resp.length());
??response.getOutputStream().write(resp.getBytes());
??
??logger.info(Thread.currentThread().getName()?+?"?進入afterConcurrentHandlingStarted方法");
?}
?
}

參考

• https://my.oschina.net/u/3768341/blog/3001731
• https://blog.csdn.net/liuchuanhong1/article/details/78744138