Spring Boot 中使用異步方法優(yōu)化 Service 邏輯，提高接口響應(yīng)速度

來(lái)源：blog.csdn.net/weixin_43441509/

article/details/119855613

1. 為什么需要異步方法?

先說(shuō)結(jié)論: 合理使用異步方法可以讓業(yè)務(wù)接口快到飛起!

異步方法適用于邏輯與邏輯之間可以相互分割互不影響的業(yè)務(wù)中, 如生成驗(yàn)證碼和發(fā)送驗(yàn)證碼組成的業(yè)務(wù), 其實(shí)無(wú)需等到真正發(fā)送成功驗(yàn)證碼才對(duì)客戶(hù)端進(jìn)行響應(yīng), 可以讓短信發(fā)送這一耗時(shí)操作轉(zhuǎn)為異步執(zhí)行, 解耦耗時(shí)操作和核心業(yè)務(wù);

同理還有文章閱讀的業(yè)務(wù)邏輯 = 查詢(xún)文章詳情 + 更新文章閱讀量后再響應(yīng)客戶(hù)端, 其實(shí)也無(wú)需等到閱讀量更新后才響應(yīng)文章詳情給客戶(hù)端, 用戶(hù)查看文章是主要邏輯, 而文章閱讀量更新是次要邏輯, 況且閱讀量就算更新失敗一點(diǎn)數(shù)據(jù)偏差也不會(huì)影響用戶(hù)閱讀因此這兩個(gè)數(shù)據(jù)庫(kù)操作之間的一致性是較弱的, 這類(lèi)都能用異步事件去優(yōu)化.

所以說(shuō): 恰當(dāng)?shù)脑谖覀兊腟ervice中加入異步方法能大大提高接口的響應(yīng)速度, 提升用戶(hù)體驗(yàn)!

同步執(zhí)行(同在一個(gè)線(xiàn)程中):

異步執(zhí)行(開(kāi)啟額外線(xiàn)程來(lái)執(zhí)行):

2. SpringBoot中的異步方法支持

其實(shí), 在SpringBoot中并不需要我們自己去創(chuàng)建維護(hù)線(xiàn)程或者線(xiàn)程池來(lái)異步的執(zhí)行方法, SpringBoot已經(jīng)提供了異步方法支持注解.

@EnableAsync?//?使用異步方法時(shí)需要提前開(kāi)啟(在啟動(dòng)類(lèi)上或配置類(lèi)上)
@Async?//?被async注解修飾的方法由SpringBoot默認(rèn)線(xiàn)程池(SimpleAsyncTaskExecutor)執(zhí)行

比如使用Spring的異步支持實(shí)現(xiàn)文章查詢(xún)并增加閱讀量

Service層:

@Service
public?class?ArticleServiceImpl?{

????//?查詢(xún)文章
????public?String?selectArticle()?{
????????//?TODO?模擬文章查詢(xún)操作
????????System.out.println("查詢(xún)?nèi)蝿?wù)線(xiàn)程"+Thread.currentThread().getName());
????????return?"文章詳情";
????}

????//?文章閱讀量+1
????@Async
????public?void?updateReadCount()?{
????????//?TODO?模擬耗時(shí)操作
????????try?{
????????????Thread.sleep(3000);
????????}?catch?(InterruptedException?e)?{
????????????e.printStackTrace();
????????}
????????System.out.println("更新任務(wù)線(xiàn)程"+Thread.currentThread().getName());
????}
}

Controller層:

@RestController
public?class?AsyncTestController?{

????@Autowired
????private?ArticleServiceImpl?articleService;

????/**
?????*?模擬獲取文章后閱讀量+1
?????*/
????@PostMapping("/article")
????public?String?getArticle()?{
????????//?查詢(xún)文章
????????String?article?=?articleService.selectArticle();
????????//?閱讀量+1
????????articleService.updateReadCount();
????????System.out.println("文章閱讀業(yè)務(wù)執(zhí)行完畢");
????????return?article;
????}

}

測(cè)試結(jié)果: 我們可以感受到接口響應(yīng)速度大大提升, 而且從日志中key看到兩個(gè)執(zhí)行任務(wù)是在不同的線(xiàn)程中執(zhí)行的

3. 自定義線(xiàn)程池執(zhí)行異步方法

SpringBoot為我們默認(rèn)提供了線(xiàn)程池(SimpleAsyncTaskExecutor)來(lái)執(zhí)行我們的異步方法, 我們也可以自定義自己的線(xiàn)程池.

第一步配置自定義線(xiàn)程池

@EnableAsync?//?開(kāi)啟多線(xiàn)程,?項(xiàng)目啟動(dòng)時(shí)自動(dòng)創(chuàng)建
@Configuration
public?class?AsyncConfig?{
????@Bean("customExecutor")
????public?ThreadPoolTaskExecutor?asyncOperationExecutor()?{
????????ThreadPoolTaskExecutor?executor?=?new?ThreadPoolTaskExecutor();
????????//?設(shè)置核心線(xiàn)程數(shù)
????????executor.setCorePoolSize(8);
????????//?設(shè)置最大線(xiàn)程數(shù)
????????executor.setMaxPoolSize(20);
????????//?設(shè)置隊(duì)列大小
????????executor.setQueueCapacity(Integer.MAX_VALUE);
????????//?設(shè)置線(xiàn)程活躍時(shí)間(秒)
????????executor.setKeepAliveSeconds(60);
????????//?設(shè)置線(xiàn)程名前綴+分組名稱(chēng)
????????executor.setThreadNamePrefix("AsyncOperationThread-");
????????executor.setThreadGroupName("AsyncOperationGroup");
????????//?所有任務(wù)結(jié)束后關(guān)閉線(xiàn)程池
????????executor.setWaitForTasksToCompleteOnShutdown(true);
????????//?初始化
????????executor.initialize();
????????return?executor;
????}
}

第二步, 在@Async注解上指定執(zhí)行的線(xiàn)程池即可

//?文章閱讀量+1
@Async("customExecutor")
public?void?updateReadCount()?{
????//?TODO?模擬耗時(shí)操作
????try?{
????????Thread.sleep(3000);
????}?catch?(InterruptedException?e)?{
????????e.printStackTrace();
????}
????System.out.println("更新文章閱讀量線(xiàn)程"+Thread.currentThread().getName());
}

5. 如何捕獲(無(wú)返回值的)異步方法中的異常

以實(shí)現(xiàn)AsyncConfigurer接口的getAsyncExecutor方法和getAsyncUncaughtExceptionHandler方法改造配置類(lèi)

自定義異常處理類(lèi)CustomAsyncExceptionHandler

@EnableAsync?//?開(kāi)啟多線(xiàn)程,?項(xiàng)目啟動(dòng)時(shí)自動(dòng)創(chuàng)建
@Configuration
public?class?AsyncConfig?implements?AsyncConfigurer?{
????@Override
????public?Executor?getAsyncExecutor()?{
????????ThreadPoolTaskExecutor?executor?=?new?ThreadPoolTaskExecutor();
????????//?設(shè)置核心線(xiàn)程數(shù)
????????executor.setCorePoolSize(8);
????????//?設(shè)置最大線(xiàn)程數(shù)
????????executor.setMaxPoolSize(20);
????????//?設(shè)置隊(duì)列大小
????????executor.setQueueCapacity(Integer.MAX_VALUE);
????????//?設(shè)置線(xiàn)程活躍時(shí)間(秒)
????????executor.setKeepAliveSeconds(60);
????????//?設(shè)置線(xiàn)程名前綴+分組名稱(chēng)
????????executor.setThreadNamePrefix("AsyncOperationThread-");
????????executor.setThreadGroupName("AsyncOperationGroup");
????????//?所有任務(wù)結(jié)束后關(guān)閉線(xiàn)程池
????????executor.setWaitForTasksToCompleteOnShutdown(true);
????????//?初始化
????????executor.initialize();
????????return?executor;
????}

????@Override
????public?AsyncUncaughtExceptionHandler?getAsyncUncaughtExceptionHandler()?{
????????return?new?CustomAsyncExceptionHandler();
????}
}

public?class?CustomAsyncExceptionHandler?implements?AsyncUncaughtExceptionHandler?{
?
????@Override
????public?void?handleUncaughtException(Throwable?throwable,?Method?method,?Object...?obj)?{
????????System.out.println("異常捕獲---------------------------------");
????????System.out.println("Exception?message?-?"?+?throwable.getMessage());
????????System.out.println("Method?name?-?"?+?method.getName());
????????for?(Object?param?:?obj)?{
????????????System.out.println("Parameter?value?-?"?+?param);
????????}
????????System.out.println("異常捕獲---------------------------------");
????}
?????
}

5. 如何獲取(有返回值)異步方法的返回值

使用Future類(lèi)及其子類(lèi)來(lái)接收異步方法返回值

注意:

• 無(wú)返回值的異步方法拋出異常不會(huì)影響Controller的主要業(yè)務(wù)邏輯
• 有返回值的異步方法拋出異常會(huì)影響Controller的主要業(yè)務(wù)邏輯

//?異步方法---------------------------------------------------------------------
@Async
????public?CompletableFuture?updateReadCountHasResult()?{
????????//?TODO?模擬耗時(shí)操作
????????try?{
????????????Thread.sleep(3000);
????????}?catch?(InterruptedException?e)?{
????????????e.printStackTrace();
????????}
????????System.out.println("更新文章閱讀量線(xiàn)程"+Thread.currentThread().getName());
????????return?CompletableFuture.completedFuture(100?+?1);
????}

//?Controller調(diào)用---------------------------------------------------------------------
@GetMapping("/article")
public?String?getArticle()?throws?ExecutionException,?InterruptedException?{
????//?查詢(xún)文章
????String?article?=?articleService.selectArticle();
????//?閱讀量+1
????CompletableFuture?future?=?articleService.updateReadCountHasResult();
????int?count?=?0;
????//?循環(huán)等待異步請(qǐng)求結(jié)果
????while?(true)?{
????????if(future.isCancelled())?{
????????????System.out.println("異步任務(wù)取消");
????????????break;
????????}
????????if?(future.isDone())?{
????????????count?=?future.get();
????????????System.out.println(count);
????????????break;
????????}
????}
????System.out.println("文章閱讀業(yè)務(wù)執(zhí)行完畢");
????return?article?+?count;
}

6. 異步方法帶來(lái)的問(wèn)題/拓展

• 異步方法只能聲明在Service方法中在Controller直接調(diào)用才會(huì)生效, 異步方法被同級(jí)Service方法調(diào)用不會(huì)生效, 很奇怪?
• 異步方法 + 事務(wù)能順利執(zhí)行嗎? 或許事務(wù)操作應(yīng)該和異步操作分離開(kāi), 被Controller層調(diào)用時(shí)事務(wù)操作在前, 異步操作在后
• 異步方法執(zhí)行失敗后對(duì)Controller前半部分的非異步操作無(wú)影響, 因此說(shuō)異步方法在整個(gè)業(yè)務(wù)邏輯中不是100%可靠的, 對(duì)于強(qiáng)一致性的業(yè)務(wù)來(lái)說(shuō)不適用
• 還是消息中間件更為強(qiáng)大, RabbitMQ, Kafka…