Resilience4j使用

介绍

Resilience4j是一款轻量级、易用、容错框架，专为 Java 8 和函数式编程而设计。

 

容错是指系统在部分组件（一个或多个）发生故障时仍能正常运作的能力。要具有这个能力，通常要包含断路器（CircuitBreaker）、并发调用隔离（Bulkhead）、限流（RateLimiter）、重试（Retry）、超时（Timeout）机制。

 

超时（Timeout）机制

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@Bulkhead(name = BACKEND_A, type = Bulkhead.Type.THREADPOOL) @TimeLimiter(name = BACKEND_A) @CircuitBreaker(name = BACKEND_A, fallbackMethod = "futureFallback") public CompletableFuture<String> fluxTimeout2() {       Random random = new Random();     int sleepTime = random.nextInt(5000);       try {         Thread.sleep(sleepTime);     } catch (InterruptedException ie) {         throw new RuntimeException(ie);     }       return CompletableFuture.completedFuture("Hello World from backend A"); }   private CompletableFuture<String> futureFallback(TimeoutException ex) {     return CompletableFuture.completedFuture("Recovered specific TimeoutException: " + ex.toString()); }

 

设置超时时间3s，application.properties

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resilience4j.timelimiter.configs.default.cancel-running-future=false resilience4j.timelimiter.configs.default.timeout-duration=3s resilience4j.timelimiter.instances.backendA.base-config=default

发起请求

http://127.0.0.1:8072/futureTimeout

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@GetMapping("futureTimeout") public String futureTimeout() throws ExecutionException, InterruptedException {     long start = System.currentTimeMillis();     String flux = businessAService.fluxTimeout2().get();     long endTime = System.currentTimeMillis();     log.info("-------futureTimeout, "+(endTime - start)+"ms");     return flux+" "+(endTime - start)+"ms"; }

　　

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-------futureTimeout, 682ms -------futureTimeout, 3010ms  //超时 -------futureTimeout, 1138ms

　　

重试（Retry） 

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@GetMapping("/getInvoice") @Retry(name = "getInvoiceRetry", fallbackMethod = "getInvoiceFallback") public String getInvoice() {     log.info("getInvoice() call starts here");     ResponseEntity<String> entity= restTemplate.getForEntity("http://127.0.0.1:8071/world", String.class);     log.info("Response :" + entity.getStatusCode());     return entity.getBody(); }   public String getInvoiceFallback(Exception e) {     log.info("---RESPONSE FROM FALLBACK METHOD---");     return "SERVICE IS DOWN, PLEASE TRY AFTER SOMETIME !!!"; }

　　发起请求

http://127.0.0.1:8072/getInvoice

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[2021-12-03 16:40:45,823] [http-nio-8072-exec-3] [INFO] -  c.f.s.c.RetryController 36 getInvoice() call starts here [2021-12-03 16:40:46,360] [http-nio-8072-exec-3] [INFO] -  c.f.s.c.RetryController 36 getInvoice() call starts here [2021-12-03 16:40:46,872] [http-nio-8072-exec-3] [INFO] -  c.f.s.c.RetryController 36 getInvoice() call starts here //重试3次 [2021-12-03 16:40:46,886] [http-nio-8072-exec-3] [INFO] -  c.f.s.c.RetryController 43 ---RESPONSE FROM FALLBACK METHOD---