提高系统吞吐量,DeferredResult 到底有多强?

Handpc
发布于 2023-4-26 15:18
浏览
0收藏

大家好,我是不才陈某~

大家都知道,​​Callable​​​和​​DeferredResult​​​可以用来进行异步请求处理。利用它们,我们可以异步生成返回值,在具体处理的过程中,我们直接在​​controller​​​中返回相应的​​Callable​​​或者​​DeferredResult​​​,在这之后,servlet线程将被释放,可用于其他连接;​​DeferredResult​​​另外会有线程来进行结果处理,并​​setResult​​。

基础准备

在正式开始之前,我们先做一点准备工作,在项目中新建了一个base模块。其中包含一些提供基础支持的java类,在其他模块中可能会用到。

ResponseMsg

我们定义了一个​​ResponseMsg​​的实体类来作为我们的返回值类型:

@Data
@NoArgsConstructor
@AllArgsConstructor
public class ResponseMsg<T> {
    private int code;
    private String msg;
    private T data;
}

非常简单,里面包含了code、msg和data三个字段,其中data为泛型类型。另外类的注解​​Data​​​、​​NoArgsConstructor​​​和​​AllArgsConstructor​​都是lombok提供的简化我们开发的,主要功能分别是,为我们的类生成set和get方法,生成无参构造器和生成全参构造器。使用idea进行开发的童鞋可以装一下lombok的支持插件。另外,lombok的依赖参见:

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok-maven</artifactId>
    <version>1.16.16.0</version>
    <type>pom</type>
</dependency>

TaskService

我们建立了一个TaskService,用来为阻塞调用和Callable调用提供实际结果处理的。代码如下:

@Service
public class TaskService {
    private static final Logger log = LoggerFactory.getLogger(TaskService.class);
    public ResponseMsg<String> getResult(){
        log.info("任务开始执行,持续等待中...");
        try {
            Thread.sleep(30000L);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        log.info("任务处理完成");
        return new ResponseMsg<String>(0,"操作成功","success");
    }
}

可以看到,里面实际提供服务的是getResult方法,这边直接返回一个​​new ResponseMsg(0,“操作成功”,“success”)​​。但是其中又特意让它sleep了30秒,模拟一个耗时较长的请求。

阻塞调用

平时我们用的最普遍的还是阻塞调用,通常请求的处理时间较短,在并发量较小的情况下,使用阻塞调用问题也不是很大。关注公众号:码猿技术专栏,回复关键词:1111 获取阿里内部Java性能调优手册!阻塞调用实现非常简单,我们首先新建一个模块​​blockingtype​​​,里面只包含一个​​controller​​​类,用来接收请求并利用​​TaskService​​来获取结果。

@RestController
public class BlockController {
    private static final Logger log = LoggerFactory.getLogger(BlockController.class);
    @Autowired
    private TaskService taskService;
    @RequestMapping(value = "/get", method = RequestMethod.GET)
    public ResponseMsg<String> getResult(){
        log.info("接收请求,开始处理...");
        ResponseMsg<String> result =  taskService.getResult();
        log.info("接收任务线程完成并退出");
        return result;
    }
}

我们请求的是​​getResult​​​方法,其中调用了​​taskService​​​,这个​​taskService​​​我们是注入得到的。关于怎么跨模块注入的,其实也非常简单,在本模块,加入对其他模块的依赖就可以了。比如这里我们在​​blockingtype​​​的​​pom.xml​​文件中加入对base模块的依赖:

<dependency>
    <groupId>com.sunny</groupId>
    <artifactId>base</artifactId>
    <version>1.0-SNAPSHOT</version>
</dependency>

然后我们看一下实际调用效果,这里我们设置端口号为8080,启动日志如下:

2018-06-24 19:02:48.514  INFO 11207 --- [           main] com.sunny.BlockApplication               : Starting BlockApplication on xdeMacBook-Pro.local with PID 11207 (/Users/zsunny/IdeaProjects/asynchronoustask/blockingtype/target/classes started by zsunny in /Users/zsunny/IdeaProjects/asynchronoustask)
2018-06-24 19:02:48.519  INFO 11207 --- [           main] com.sunny.BlockApplication               : No active profile set, falling back to default profiles: default
2018-06-24 19:02:48.762  INFO 11207 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4445629: startup date [Sun Jun 24 19:02:48 CST 2018]; root of context hierarchy
2018-06-24 19:02:50.756  INFO 11207 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2018-06-24 19:02:50.778  INFO 11207 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-06-24 19:02:50.780  INFO 11207 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.23
2018-06-24 19:02:50.922  INFO 11207 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-06-24 19:02:50.922  INFO 11207 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2200 ms
2018-06-24 19:02:51.156  INFO 11207 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-06-24 19:02:51.162  INFO 11207 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-06-24 19:02:51.163  INFO 11207 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-06-24 19:02:51.163  INFO 11207 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-06-24 19:02:51.163  INFO 11207 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-06-24 19:02:51.620  INFO 11207 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4445629: startup date [Sun Jun 24 19:02:48 CST 2018]; root of context hierarchy
2018-06-24 19:02:51.724  INFO 11207 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/get],methods=[GET]}" onto public com.sunny.entity.ResponseMsg<java.lang.String> com.sunny.controller.BlockController.getResult()
2018-06-24 19:02:51.730  INFO 11207 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-06-24 19:02:51.731  INFO 11207 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-06-24 19:02:51.780  INFO 11207 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 19:02:51.780  INFO 11207 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 19:02:51.838  INFO 11207 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 19:02:52.126  INFO 11207 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-06-24 19:02:52.205  INFO 11207 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2018-06-24 19:02:52.211  INFO 11207 --- [           main] com.sunny.BlockApplication               : Started BlockApplication in 5.049 seconds (JVM running for 6.118)

可以看到顺利启动了,那么我们就来访问一下:

http://localhost:8080/get

等待了大概30秒左右,得到json数据:

{"code":0,"msg":"操作成功","data":"success"}

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

然后我们来看看控制台的日志:

2018-06-24 19:04:07.315  INFO 11207 --- [nio-8080-exec-1] com.sunny.controller.BlockController     : 接收请求,开始处理...
2018-06-24 19:04:07.316  INFO 11207 --- [nio-8080-exec-1] com.sunny.service.TaskService            : 任务开始执行,持续等待中...
2018-06-24 19:04:37.322  INFO 11207 --- [nio-8080-exec-1] com.sunny.service.TaskService            : 任务处理完成
2018-06-24 19:04:37.322  INFO 11207 --- [nio-8080-exec-1] com.sunny.controller.BlockController     : 接收任务线程完成并退出

可以看到在“​​ResponseMsg result = taskService.getResult();​​​”的时候是阻塞了大约30秒钟,随后才执行它后面的打印语句“​​log.info(“接收任务线程完成并退出”);​​”。

Callable异步调用

涉及到较长时间的请求处理的话,比较好的方式是用异步调用,比如利用​​Callable​​​返回结果。异步主要表现在,接收请求的​​servlet​​​可以不用持续等待结果产生,而可以被释放去处理其他事情。当然,在调用者来看的话,其实还是表现在持续等待30秒。这有利于服务端提供更大的并发处理量。这里我们新建一个​​callabledemo​​​模块,在这个模块中,我们一样只包含一个​​TaskController​​​,另外也是需要加入base模块的依赖。只不过这里我们的返回值不是​​ResponseMsg​​​类型了,而是一个​​Callable​​类型。

@RestController
public class TaskController {
    private static final Logger log = LoggerFactory.getLogger(TaskController.class);

    @Autowired
    private TaskService taskService;

    @RequestMapping(value = "/get",method = RequestMethod.GET)
    public Callable<ResponseMsg<String>> getResult(){

        log.info("接收请求,开始处理...");

        Callable<ResponseMsg<String>> result = (()->{
            return taskService.getResult();
        });

        log.info("接收任务线程完成并退出");
        return result;
    }
}

在里面,我们创建了一个​​Callable​​​类型的变量result,并实现了它的call方法,在call方法中,我们也是调用​​taskService​​​的​​getResult​​​方法得到返回值并返回。下一步我们就运行一下这个模块,这里我们在模块的​​application.yml​​中设置端口号为8081:

server:
  port: 8081

启动,可以看到控制台的消息:

2018-06-24 19:38:14.658  INFO 11226 --- [           main] com.sunny.CallableApplication            : Starting CallableApplication on xdeMacBook-Pro.local with PID 11226 (/Users/zsunny/IdeaProjects/asynchronoustask/callabledemo/target/classes started by zsunny in /Users/zsunny/IdeaProjects/asynchronoustask)
2018-06-24 19:38:14.672  INFO 11226 --- [           main] com.sunny.CallableApplication            : No active profile set, falling back to default profiles: default
2018-06-24 19:38:14.798  INFO 11226 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4445629: startup date [Sun Jun 24 19:38:14 CST 2018]; root of context hierarchy
2018-06-24 19:38:16.741  INFO 11226 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8081 (http)
2018-06-24 19:38:16.762  INFO 11226 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-06-24 19:38:16.764  INFO 11226 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.23
2018-06-24 19:38:16.918  INFO 11226 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-06-24 19:38:16.919  INFO 11226 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2126 ms
2018-06-24 19:38:17.144  INFO 11226 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-06-24 19:38:17.149  INFO 11226 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-06-24 19:38:17.150  INFO 11226 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-06-24 19:38:17.150  INFO 11226 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-06-24 19:38:17.150  INFO 11226 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-06-24 19:38:17.632  INFO 11226 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4445629: startup date [Sun Jun 24 19:38:14 CST 2018]; root of context hierarchy
2018-06-24 19:38:17.726  INFO 11226 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/get],methods=[GET]}" onto public java.util.concurrent.Callable<com.sunny.entity.ResponseMsg<java.lang.String>> com.sunny.controller.TaskController.getResult()
2018-06-24 19:38:17.731  INFO 11226 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-06-24 19:38:17.733  INFO 11226 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-06-24 19:38:17.777  INFO 11226 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 19:38:17.777  INFO 11226 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 19:38:17.825  INFO 11226 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 19:38:18.084  INFO 11226 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-06-24 19:38:18.176  INFO 11226 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8081 (http)
2018-06-24 19:38:18.183  INFO 11226 --- [           main] com.sunny.CallableApplication            : Started CallableApplication in 4.538 seconds (JVM running for 5.327)

完美启动了,然后我们还是一样,访问一下:

http://localhost:8081/get

在大约等待了30秒左右,我们在浏览器上得到json数据:

{"code":0,"msg":"操作成功","data":"success"}

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

和阻塞调用的结果一样——当然一样啦,都是同​​taskService​​中得到的结果。然后我们看看控制台的消息:

2018-06-24 19:39:07.738  INFO 11226 --- [nio-8081-exec-1] com.sunny.controller.TaskController      : 接收请求,开始处理...
2018-06-24 19:39:07.740  INFO 11226 --- [nio-8081-exec-1] com.sunny.controller.TaskController      : 接收任务线程完成并退出
2018-06-24 19:39:07.753  INFO 11226 --- [      MvcAsync1] com.sunny.service.TaskService            : 任务开始执行,持续等待中...
2018-06-24 19:39:37.756  INFO 11226 --- [      MvcAsync1] com.sunny.service.TaskService            : 任务处理完成

很显然,这里的消息出现的顺序和阻塞模式有所不同了,这里在“接收请求,开始处理…”之后直接打印了“接收任务线程完成并退出”。而不是先出现“任务处理完成”后再出现“接收任务线程完成并退出”。这就说明,这里没有阻塞在从​​taskService​​​中获得数据的地方,​​controller​​中直接执行后面的部分(这里可以做其他很多事,不仅仅是打印日志)。

DeferredResult异步调用

前面铺垫了那么多,还是主要来说​​DeferredResult​​​的;和​​Callable​​​一样,​​DeferredResult​​​也是为了支持异步调用。两者的主要差异,Sunny觉得主要在​​DeferredResult​​​需要自己用线程来处理结果​​setResult​​​,而​​Callable​​​的话不需要我们来维护一个结果处理线程。总体来说,​​Callable​​​的话更为简单,同样的也是因为简单,灵活性不够;相对地,​​DeferredResult​​​更为复杂一些,但是又极大的灵活性。在可以用​​Callable​​​的时候,直接用​​Callable​​​;而遇到​​Callable​​​没法解决的场景的时候,可以尝试使用​​DeferredResult​​​。这里Sunny将会设计两个​​DeferredResult​​使用场景。

场景一:
  • 创建一个持续在随机间隔时间后从任务队列中获取任务的线程
  • 访问​​controller​​​中的方法,创建一个​​DeferredResult​​,设定超时时间和超时返回对象
  • 设定​​DeferredResult​​的超时回调方法和完成回调方法
  • 将​​DeferredResult​​放入任务中,并将任务放入任务队列
  • 步骤1中的线程获取到任务队列中的任务,并产生一个随机结果返回
  • 场景其实非常简单,接下来我们来看看具体的实现。首先,我们还是来看任务实体类是怎么样的。

/**
 * 任务实体类
 */
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Task {
    private int taskId;
    private DeferredResult<ResponseMsg<String>> taskResult;

    @Override
    public String toString() {
        return "Task{" +
                "taskId=" + taskId +
                ", taskResult" + "{responseMsg=" + taskResult.getResult() + "}" +
                '}';
    }
}

看起来非常简单,成员变量又​​taskId​​​和​​taskResult​​​,前者是int类型,后者为我们的​​DeferredResult​​​类型,它的泛型类型为​​ResponseMsg​​​,注意这里用到​​ResponseMsg​​​,所以也需要导入base模块的依赖。另外注解之前已经说明了,不过这里再提一句,​​@Data​​​注解也包含了toString的重写,但是这里为了知道具体的​​ResponseMsg​​的内容,Sunny特意手动重写。看完Task类型,我们再来看看任务队列。

@Component
public class TaskQueue {
    private static final Logger log = LoggerFactory.getLogger(TaskQueue.class);
    private static final int QUEUE_LENGTH = 10;
    private BlockingQueue<Task> queue = new LinkedBlockingDeque<>(QUEUE_LENGTH);
    private int taskId = 0;
    /**
     * 加入任务
     *     @param deferredResult
     */
    public void put(DeferredResult<ResponseMsg<String>> deferredResult){

        taskId++;
        log.info("任务加入队列,id为:{}",taskId);
        queue.offer(new Task(taskId,deferredResult));
    }

    /**
     * 获取任务
     *     @return
     *     @throws InterruptedException
     */
    public Task take() throws InterruptedException {
        Task task = queue.poll();
        log.info("获得任务:{}",task);
        return task;
    }
}

这里我们将它作为一个bean,之后会在其他bean中注入,这里实际的队列为成员变量queue,它是​​LinkedBlockingDeque​​​类型的。还有一个成员变量为taskId,是用于自动生成任务id的,并且在加入任务的方法中实现自增,以确保每个任务的id唯一性。方法的话又put和take方法,分别用于向队列中添加任务和取出任务;其中,对queue的操作,分别用了offer和poll,这样是实现一个非阻塞的操作,并且在队列为空和队列已满的情况下不会抛出异常。另外,大家实现的时候,可以考虑使用​​ConcurrentLinkedQueue​​​来高效处理并发,因为它属于无界非阻塞队列,使用过程中需要考虑可能造成的OOM问题。Sunny这里选择阻塞队列​​LinkedBlockingDeque​​​,它底层使用加锁进行了同步;但是这里使用了​​TaskQueue​​进行封装,处理过程中有一些额外操作,调用时需要加锁以防发生某些意料之外的问题。

然后我们来看步骤1中的,启动一个持续从任务队列中获取任务的线程的具体实现。

@Component
public class TaskExecute {
    private static final Logger log = LoggerFactory.getLogger(TaskExecute.class);
    private static final Random random = new Random();

    //默认随机结果的长度
    private static final int DEFAULT_STR_LEN = 10;
    
    //用于生成随机结果
    private static final String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

    @Autowired
    private TaskQueue taskQueue;
    /**
     * 初始化启动
     */
    @PostConstruct
    public void init(){
        log.info("开始持续处理任务");
        new Thread(this::execute).start();
    }

    /**
     * 持续处理
     * 返回执行结果
     */
    private void execute(){
        while (true){
            try {
                //取出任务
                Task task;
                synchronized (taskQueue) {
                    task = taskQueue.take();

                }

                if(task != null) {

                    //设置返回结果
                    String randomStr = getRandomStr(DEFAULT_STR_LEN);
                    ResponseMsg<String> responseMsg = new ResponseMsg<String>(0, "success", randomStr);
                    log.info("返回结果:{}", responseMsg);
                    task.getTaskResult().setResult(responseMsg);
                }
                int time = random.nextInt(10);
                log.info("处理间隔:{}秒",time);
                Thread.sleep(time*1000L);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    /**
     * 获取长度为len的随机串
     *     @param len
     *     @return
     */
    private String getRandomStr(int len){
        int maxInd = str.length();
        StringBuilder sb = new StringBuilder();
        int ind;

        for(int i=0;i<len;i++){
            ind = random.nextInt(maxInd);
            sb.append(str.charAt(ind));
        }
        return String.valueOf(sb);
    }
}

这里,我们注入了​​TaskQueue​​​,成员变量比较简单并且有注释,不再说明,主要来看方法。先看一下最后一个方法​​getRandomStr​​​,很显然,这是一个获得长度为len的随机串的方法,访问限定为private,为类中其他方法服务的。然后我们看init方法,它执行的其实就是开启了一个线程并且执行execute方法,注意一下它上面的​​@PostContruct​​​注解,这个注解就是在这个bean初始化的时候就执行这个方法。所以我们需要关注的实际逻辑在​​execute​​​方法中。可以看到,在​​execute​​​方法中,用了一个​​while(true)​​​来保证线程持续运行。因为是并发环境下,考虑对​​taskQueue​​​加锁,从中取出任务;如果任务不为空,获取用​​getRandomStr​​​生成一个随机结果并用​​setResult​​​方法进行返回。最后可以看到,利用random生成来一个​​[0,10)​​​的随机数,并让线程sleep相应的秒数。这里注意一下,需要设定一个时间间隔,否则,先线程持续跑会出现CPU负载过高的情况。接下来我们就看看​​controller​​是如何处理的。

@RestController
public class TaskController {
    private static final Logger log = LoggerFactory.getLogger(TaskController.class);

    //超时结果
    private static final ResponseMsg<String> OUT_OF_TIME_RESULT = new ResponseMsg<>(-1,"超时","out of time");

    //超时时间
    private static final long OUT_OF_TIME = 3000L;

    @Autowired
    private TaskQueue taskQueue;

    @RequestMapping(value = "/get",method = RequestMethod.GET)
    public DeferredResult<ResponseMsg<String>> getResult() {

        log.info("接收请求,开始处理...");

        //建立DeferredResult对象,设置超时时间,以及超时返回超时结果
        DeferredResult<ResponseMsg<String>> result = new DeferredResult<>(OUT_OF_TIME, OUT_OF_TIME_RESULT);

        result.onTimeout(() -> {
            log.info("调用超时");
        });

        result.onCompletion(() -> {
            log.info("调用完成");
        });

        //并发,加锁
        synchronized (taskQueue) {
            taskQueue.put(result);
        }
        log.info("接收任务线程完成并退出");
        return result;
    }
}

这里我们同样注入了​​taskQueue​​​。请求方法就只有一个​​getResult​​​,返回值为​​DeferredResult<ResponseMsg>​​​。这里我们首先创建了​​DeferredResult​​​对象result并且设定超时时间和超时返回结果;随后设定result的​​onTimeout​​​和​​onCompletion​​​方法,其实就是传入两个​​Runnable​​​对象来实现回调的效果;之后就是加锁并且将result加入任务队列中。总体来说,场景不算非常复杂,看到这里大家应该都能基本了解了。然后我们来跑一下测试一下。我们在​​application.yml​​中设定端口为8082:

server:
  port: 8082

启动模块,控制台信息如下:

2018-06-24 21:49:28.815  INFO 11322 --- [           main] com.sunny.DeferredResultApplication      : Starting DeferredResultApplication on xdeMacBook-Pro.local with PID 11322 (/Users/zsunny/IdeaProjects/asynchronoustask/deferredresultdemo/target/classes started by zsunny in /Users/zsunny/IdeaProjects/asynchronoustask)
2018-06-24 21:49:28.821  INFO 11322 --- [           main] com.sunny.DeferredResultApplication      : No active profile set, falling back to default profiles: default
2018-06-24 21:49:29.010  INFO 11322 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5ccddd20: startup date [Sun Jun 24 21:49:28 CST 2018]; root of context hierarchy
2018-06-24 21:49:30.971  INFO 11322 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8082 (http)
2018-06-24 21:49:30.980  INFO 11322 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-06-24 21:49:30.981  INFO 11322 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.23
2018-06-24 21:49:31.062  INFO 11322 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-06-24 21:49:31.063  INFO 11322 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2066 ms
2018-06-24 21:49:31.207  INFO 11322 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-06-24 21:49:31.212  INFO 11322 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-06-24 21:49:31.213  INFO 11322 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-06-24 21:49:31.213  INFO 11322 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-06-24 21:49:31.213  INFO 11322 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-06-24 21:49:31.247  INFO 11322 --- [           main] com.sunny.bean.TaskExecute               : 开始持续处理任务
2018-06-24 21:49:31.249  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskQueue                 : 获得任务:null
2018-06-24 21:49:31.250  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskExecute               : 处理间隔:6秒
2018-06-24 21:49:31.498  INFO 11322 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5ccddd20: startup date [Sun Jun 24 21:49:28 CST 2018]; root of context hierarchy
2018-06-24 21:49:31.572  INFO 11322 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/get],methods=[GET]}" onto public org.springframework.web.context.request.async.DeferredResult<com.sunny.entity.ResponseMsg<java.lang.String>> com.sunny.controller.TaskController.getResult()
2018-06-24 21:49:31.576  INFO 11322 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-06-24 21:49:31.577  INFO 11322 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-06-24 21:49:31.602  INFO 11322 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 21:49:31.602  INFO 11322 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 21:49:31.628  INFO 11322 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-24 21:49:31.811  INFO 11322 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-06-24 21:49:31.892  INFO 11322 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8082 (http)
2018-06-24 21:49:31.897  INFO 11322 --- [           main] com.sunny.DeferredResultApplication      : Started DeferredResultApplication in 3.683 seconds (JVM running for 4.873)
2018-06-24 21:49:37.254  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskQueue                 : 获得任务:null
2018-06-24 21:49:37.254  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskExecute               : 处理间隔:6秒

首先程序完美启动,这没有问题,然后我们注意这几条信息:

2018-06-24 21:49:31.247  INFO 11322 --- [           main] com.sunny.bean.TaskExecute               : 开始持续处理任务
2018-06-24 21:49:31.249  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskQueue                 : 获得任务:null
2018-06-24 21:49:31.250  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskExecute               : 处理间隔:6秒

这说明我们​​TaskExecute​​中已经成功启动了持续获取任务的线程。接着,我们还是访问一下:

http://localhost:8082/get

这一回等待了若干秒就出现了结果:

{"code":0,"msg":"success","data":"CEUO2lmMJr"}

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

可以看到我们的随机串是​​CEUO2lmMJr​​。再一次请求又会出现不同的随机串。再看一下我们控制台的相关信息:

2018-06-24 21:51:04.303  INFO 11322 --- [nio-8082-exec-1] com.sunny.controller.TaskController      : 接收请求,开始处理...
2018-06-24 21:51:04.304  INFO 11322 --- [nio-8082-exec-1] com.sunny.bean.TaskQueue                 : 任务加入队列,id为:1
2018-06-24 21:51:04.304  INFO 11322 --- [nio-8082-exec-1] com.sunny.controller.TaskController      : 接收任务线程完成并退出
2018-06-24 21:51:04.323  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskQueue                 : 获得任务:Task{taskId=1, taskResult{responseMsg=null}}
2018-06-24 21:51:04.323  INFO 11322 --- [       Thread-8] com.sunny.bean.TaskExecute               : 返回结果:ResponseMsg(code=0, msg=success, data=CEUO2lmMJr)

也是符合我们的预期,请求进来进入队列中,由​​TaskExecute​​获取请求并进行处理结果返回。

场景二
  • 用户发送请求到​​TaskController​​​的​​getResult​​​方法,该方法接收到请求,创建一个​​DeferredResult​​,设定超时时间和超时返回对象
  • 设定​​DeferredResult​​​的超时回调方法和完成回调方法,超时和完成都会将本次请求产生的​​DeferredResult​​从集合中remove
  • 将​​DeferredResult​​放入集合中
  • 另有一个​​TaskExecuteController​​​,访问其中一个方法,可取出集合中的等待返回的​​DeferredResult​​对象,并将传入的参数设定为结果

首先我们来看看​​DeferredResult​​的集合类:

@Component
@Data
public class TaskSet {
    private Set<DeferredResult<ResponseMsg<String>>> set = new HashSet<>();

}

非常简单,只包含了一个HashSet的成员变量。这里可以考虑用​​ConcurrentHashMap​​​来实现高效并发,Sunny这里简单实用HashSet,配合加锁实现并发处理。然后我们看看发起调用的​​Controller​​代码:

@RestController
public class TaskController {

    private Logger log = LoggerFactory.getLogger(TaskController.class);

    //超时结果
    private static final ResponseMsg<String> OUT_OF_TIME_RESULT = new ResponseMsg<>(-1,"超时","out of time");

    //超时时间
    private static final long OUT_OF_TIME = 60000L;

    @Autowired
    private TaskSet taskSet;

    @RequestMapping(value = "/get",method = RequestMethod.GET)
    public DeferredResult<ResponseMsg<String>> getResult(){

        log.info("接收请求,开始处理...");

        //建立DeferredResult对象,设置超时时间,以及超时返回超时结果
        DeferredResult<ResponseMsg<String>> result = new DeferredResult<>(OUT_OF_TIME, OUT_OF_TIME_RESULT);

        result.onTimeout(() -> {
            log.info("调用超时,移除任务,此时队列长度为{}",taskSet.getSet().size());
            
            synchronized (taskSet.getSet()) {

                taskSet.getSet().remove(result);
            }
        });

        result.onCompletion(() -> {
            log.info("调用完成,移除任务,此时队列长度为{}",taskSet.getSet().size());
            
            synchronized (taskSet.getSet()) {

                taskSet.getSet().remove(result);
            }
        });

        //并发,加锁
        synchronized (taskSet.getSet()) {

            taskSet.getSet().add(result);

        }
        log.info("加入任务集合,集合大小为:{}",taskSet.getSet().size());

        log.info("接收任务线程完成并退出");

        return result;
    }
}

和场景一中有些类似,但是注意这里在​​onTimeout​​​和​​onCompletion​​​中都多了一个移除元素的操作,这也就是每次调用结束,需要将集合中的​​DeferredResult​​​对象移除,即集合中保存的都是等待请求结果的​​DeferredResult​​​对象。然后我们看处理请求结果的​​Controller​​:

@RestController
public class TaskExecuteController {

    private static final Logger log = LoggerFactory.getLogger(TaskExecuteController.class);

    @Autowired
    private TaskSet taskSet;

    @RequestMapping(value = "/set/{result}",method = RequestMethod.GET)
    public String setResult(@PathVariable("result") String result){

        ResponseMsg<String> res = new ResponseMsg<>(0,"success",result);

        log.info("结果处理开始,得到输入结果为:{}",res);

        Set<DeferredResult<ResponseMsg<String>>> set = taskSet.getSet();

        synchronized (set){

            set.forEach((deferredResult)->{deferredResult.setResult(res);});

        }
        return "Successfully set result: " + result;
    }
}

看起来非常简单,只是做了两个操作,接收得到的参数并利用参数生成一个​​ResponseMsg​​​对象,随后将集合中的所有​​DeferredResult​​​都设定结果为根据参数生成的​​ResponseMsg​​对象。最后返回一个提示:成功设置结果…好了,话不多说,我们来启动测试验证一下。我们说一下验证的过程,我们同时打开两个请求,然后再设定一个结果,最后两个请求都会得到这个结果。当然同时多个或者一个请求也是一样。这里有一个地方需要注意一下:

浏览器可能会对相同的url请求有缓存策略,也就是同时两个标签向同一个url发送请求,浏览器只会先发送一个请求,等一个请求结束才会再发送另外一个请求。

这样,我们考虑从两个浏览器中发送请求:

localhost:8083/get

然后随便找其中一个,发送请求来设置结果:

http://localhost:8083/set/aaa

首先我们先启动模块,可以从控制台中看到完美启动管理了:

2018-06-25 00:18:44.379  INFO 12688 --- [           main] com.sunny.DeferredResultApplication      : Starting DeferredResultApplication on xdeMacBook-Pro.local with PID 12688 (/Users/zsunny/IdeaProjects/asynchronoustask/deferredresultdemo2/target/classes started by zsunny in /Users/zsunny/IdeaProjects/asynchronoustask)
2018-06-25 00:18:44.382  INFO 12688 --- [           main] com.sunny.DeferredResultApplication      : No active profile set, falling back to default profiles: default
2018-06-25 00:18:44.489  INFO 12688 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@96def03: startup date [Mon Jun 25 00:18:44 CST 2018]; root of context hierarchy
2018-06-25 00:18:45.650  INFO 12688 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8083 (http)
2018-06-25 00:18:45.658  INFO 12688 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-06-25 00:18:45.659  INFO 12688 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.23
2018-06-25 00:18:45.722  INFO 12688 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-06-25 00:18:45.723  INFO 12688 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1241 ms
2018-06-25 00:18:45.817  INFO 12688 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-06-25 00:18:45.821  INFO 12688 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-06-25 00:18:45.821  INFO 12688 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-06-25 00:18:45.821  INFO 12688 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-06-25 00:18:45.821  INFO 12688 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-06-25 00:18:46.150  INFO 12688 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@96def03: startup date [Mon Jun 25 00:18:44 CST 2018]; root of context hierarchy
2018-06-25 00:18:46.197  INFO 12688 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/get],methods=[GET]}" onto public org.springframework.web.context.request.async.DeferredResult<com.sunny.entity.ResponseMsg<java.lang.String>> com.sunny.controller.TaskController.getResult()
2018-06-25 00:18:46.199  INFO 12688 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/set/{result}],methods=[GET]}" onto public java.lang.String com.sunny.controller.TaskExecuteController.setResult(java.lang.String)
2018-06-25 00:18:46.202  INFO 12688 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-06-25 00:18:46.202  INFO 12688 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-06-25 00:18:46.237  INFO 12688 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-25 00:18:46.238  INFO 12688 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-25 00:18:46.262  INFO 12688 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-25 00:18:46.362  INFO 12688 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-06-25 00:18:46.467  INFO 12688 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8083 (http)
2018-06-25 00:18:46.472  INFO 12688 --- [           main] com.sunny.DeferredResultApplication      : Started DeferredResultApplication in 2.675 seconds (JVM running for 3.623)

完美启动,接下来Sunny在火狐中发起一个请求

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

可以看到正在等待请求结果。随后我们在谷歌浏览器中发起请求

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

两个请求同时处于等待状态,这时候我们看一下控制台信息:

2018-06-25 00:22:34.642  INFO 12688 --- [nio-8083-exec-6] com.sunny.controller.TaskController      : 接收请求,开始处理...
2018-06-25 00:22:34.642  INFO 12688 --- [nio-8083-exec-6] com.sunny.controller.TaskController      : 加入任务集合,集合大小为:1
2018-06-25 00:22:34.642  INFO 12688 --- [nio-8083-exec-6] com.sunny.controller.TaskController      : 接收任务线程完成并退出
2018-06-25 00:22:37.332  INFO 12688 --- [nio-8083-exec-7] com.sunny.controller.TaskController      : 接收请求,开始处理...
2018-06-25 00:22:37.332  INFO 12688 --- [nio-8083-exec-7] com.sunny.controller.TaskController      : 加入任务集合,集合大小为:2
2018-06-25 00:22:37.332  INFO 12688 --- [nio-8083-exec-7] com.sunny.controller.TaskController      : 接收任务线程完成并退出

可以看到两个请求都已经接收到了,并且加入了队列。这时候,我们再发送一个设置结果的请求。

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

随后我们查看两个调用请求的页面,发现页面已经不在等待状态中了,都已经得到了结果。

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

另外,再给大家展示一下超时的结果,即我们发起调用请求,但是不发起设置结果的请求,等待时间结束。

提高系统吞吐量,DeferredResult 到底有多强?-鸿蒙开发者社区

查看控制台信息:

2018-06-25 00:26:15.898  INFO 12688 --- [nio-8083-exec-4] com.sunny.controller.TaskController      : 接收请求,开始处理...
2018-06-25 00:26:15.898  INFO 12688 --- [nio-8083-exec-4] com.sunny.controller.TaskController      : 加入任务集合,集合大小为:1
2018-06-25 00:26:15.898  INFO 12688 --- [nio-8083-exec-4] com.sunny.controller.TaskController      : 接收任务线程完成并退出
2018-06-25 00:27:16.014  INFO 12688 --- [nio-8083-exec-5] com.sunny.controller.TaskController      : 调用超时,移除任务,此时队列长度为1
2018-06-25 00:27:16.018  INFO 12688 --- [nio-8083-exec-5] com.sunny.controller.TaskControl


文章转载自公众号: 码猿技术专栏

分类
已于2023-4-26 15:18:31修改
收藏
回复
举报
回复
    相关推荐