7 种提升 Spring Boot 吞吐量神技

◆ 一、异步执行

实现方式二种：

1. 使用异步注解@aysnc、启动类：添加@EnableAsync注解

2. JDK 8本身有一个非常好用的Future类——CompletableFuture

@AllArgsConstructor
publicclassAskThreadimplementsRunnable{
private CompletableFuture<Integer> re = ;
publicvoidrun {
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;
//模拟长时间的计算过程
Thread.sleep(1000);
//告知完成结果
future.complete(60);
}
}

在该示例中，启动一个线程，此时AskThread对象还没有拿到它需要的数据，执行到myRe = re.get * re.get会阻塞。我们用休眠1秒来模拟一个长时间的计算过程，并将计算结果告诉future执行结果，AskThread线程将会继续执行。如果您正在学习Spring Boot，那么推荐一个连载多年还在继续更新的免费教程：
http://blog.didispace.com/spring-boot-learning-2x/

public classCalc{
public static Integer calc(Integer para) {try {
//模拟一个长时间的执行
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方法构造一个CompletableFuture实例，在supplyAsync方法中，它会在一个新线程中，执行传入的参数。在这里它会执行calc方法，这个方法可能是比较慢的，但这并不影响CompletableFuture实例的构造速度，supplyAsync会立即返回。

而返回的CompletableFuture实例就可以作为这次调用的契约，在将来任何场合，用于获得最终的计算结果。最近整理了一份最新的面试资料，里面收录了2021年各个大厂的面试题，打算跳槽的小伙伴不要错过，点击领取吧！

supplyAsync用于提供返回值的情况，CompletableFuture还有一个不需要返回值的异步调用方法runAsync(Runnable runnable),一般我们在优化Controller时，使用这个方法比较多。这两个方法如果在不指定线程池的情况下，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，当主线程结束时，这些线程无论执行完毕都会退出系统。

核心代码：

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

异步调用使用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去处理
* 然后DispatcherServlet还有所有的spring拦截器都退出主线程，然后把response保持打开的状态
* 当Callable执行结束之后，springmvc就会重新启动分配一个request请求，然后DispatcherServlet就重新
* 调用和处理Callable异步执行的返回结果， 然后返回视图
*
* @return
*/
@GetMapping("/hello")
public Callable<String> helloController {
logger.info(Thread.currentThread.getName + " 进入helloController方法");
Callable<String> callable = new Callable<String> {@Override
public String call throws Exception {
logger.info(Thread.currentThread.getName + " 进入call方法");
String say = hello.sayHello;logger.info(Thread.currentThread.getName + " 从helloService方法返回");
return say;
}};logger.info(Thread.currentThread.getName + " 从helloController方法返回");
return callable;
}}

异步调用的方式 WebAsyncTask

@RestController
public class HelloController {private static final Logger logger = LoggerFactory.getLogger(HelloController.class);@Autowiredprivate HelloService hello;/**
* 带超时时间的异步请求 通过WebAsyncTask自定义客户端超时间
*
* @return
*/
@GetMapping("/world")
public WebAsyncTask<String> worldController {logger.info(Thread.currentThread.getName + " 进入helloController方法");
// 3s钟没返回，则认为超时
WebAsyncTask<String> webAsyncTask = new WebAsyncTask<>(3000, new Callable<String> {
@Overridepublic String call throws Exception {logger.info(Thread.currentThread.getName + " 进入call方法");
String say = hello.sayHello;
logger.info(Thread.currentThread.getName + " 从helloService方法返回");
return say;
}});logger.info(Thread.currentThread.getName + " 从helloController方法返回");
webAsyncTask.onCompletion(new Runnable {@Overridepublic void run {logger.info(Thread.currentThread.getName + " 执行完毕");
}});webAsyncTask.onTimeout(new Callable<String> {@Overridepublic String call throws Exception {logger.info(Thread.currentThread.getName + " onTimeout");
// 超时的时候，直接抛异常，让外层统一处理超时异常
throw new TimeoutException("调用超时");
}});return webAsyncTask;
}/*** 异步调用，异常处理，详细的处理流程见MyExceptionHandler类** @return*/
@GetMapping("/exception")
public WebAsyncTask<String> exceptionController {
logger.info(Thread.currentThread.getName + " 进入helloController方法");
Callable<String> callable = new Callable<String> {
@Override
public String call throws Exception {
logger.info(Thread.currentThread.getName + " 进入call方法");
throw new TimeoutException("调用超时!");
}
};
logger.info(Thread.currentThread.getName + " 从helloController方法返回");
return new WebAsyncTask<>(20000, callable);
}
}

◆ 二、增加内嵌Tomcat的最大连接数

@Configuration
publicclassTomcatConfig{
@Bean
public ConfigurableServletWebServerFactory webServerFactory {
TomcatServletWebServerFactory tomcatFactory = new TomcatServletWebServerFactory;
tomcatFactory.addConnectorCustomizers(new MyTomcatConnectorCustomizer);
tomcatFactory.setPort(8005);
tomcatFactory.setContextPath("/api-g");
return tomcatFactory;
}classMyTomcatConnectorCustomizerimplementsTomcatConnectorCustomizer{
publicvoidcustomize(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);
}
}
}

◆ 三、使用@ComponentScan定位扫包比@SpringBootApplication扫包更快

◆ 四、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>

◆ 五、使用 BufferedWriter 进行缓冲

◆ 六、Deferred方式实现异步调用

@RestController
publicclassAsyncDeferredController{
private final Logger logger = LoggerFactory.getLogger(this.getClass);
private final LongTimeTask taskService;@AutowiredpublicAsyncDeferredController(LongTimeTask taskService) {
this.taskService = taskService;
}@GetMapping("/deferred")
public DeferredResult<String> executeSlowTask {logger.info(Thread.currentThread.getName + "进入executeSlowTask方法");
DeferredResult<String> deferredResult = new DeferredResult<>;
// 调用长时间执行任务
taskService.execute(deferredResult);// 当长时间任务中使用deferred.setResult("world");这个方法时，会从长时间任务中返回，继续controller里面的流程
logger.info(Thread.currentThread.getName + "从executeSlowTask方法返回");
// 超时的回调方法
deferredResult.onTimeout(new Runnable{
@Overridepublicvoidrun {
logger.info(Thread.currentThread.getName + " onTimeout");
// 返回超时信息
deferredResult.setErrorResult("time out!");
}});// 处理完成的回调方法，无论是超时还是处理成功，都会进入这个回调方法
deferredResult.onCompletion(new Runnable{
@Overridepublicvoidrun {
logger.info(Thread.currentThread.getName + " onCompletion");
}});return deferredResult;
}}

◆ 七、异步调用可以使用AsyncHandlerInterceptor进行拦截

@Component
publicclassMyAsyncHandlerInterceptorimplementsAsyncHandlerInterceptor{
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+ "服务调用完成，返回结果给客户端");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
if( != ex){
System.out.println("发生异常:"+ex.getMessage);
}
}
@Override
public void afterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
// 拦截之后，重新写回数据，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方法");
}
}

参考

https://my.oschina.net/u/3768341/blog/3001731

https://blog.csdn.net/liuchuanhong1/article/details/78744138

来源：

https://xhcom.blog.csdn.net/article/details/88046026

往期推荐