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

平时我们用得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。 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"}

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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"}

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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:

/** * 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。扩展:最全的java面试题库

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。扩展:最全的java面试题库

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"}

如何测试raid 回写缓存性能 提高系统吞吐量的一把利器(3)

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

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。扩展:最全的java面试题库

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

如何测试raid 回写缓存性能 提高系统吞吐量的一把利器(4)

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

如何测试raid 回写缓存性能 提高系统吞吐量的一把利器(5)

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。

如何测试raid 回写缓存性能 提高系统吞吐量的一把利器(6)

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。

如何测试raid 回写缓存性能 提高系统吞吐量的一把利器(7)

如何测试raid 回写缓存性能 提高系统吞吐量的一把利器(8)

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。

如何测试raid 回写缓存性能 提高系统吞吐量的一把利器(9)

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.TaskController : 调用完成,移除任务,此时队列长度为0

,