java - CompletableFuture error: HttpServerError: 503 Service Unavailable

Question

I use Springboot2 and Java 8. I have been banging my head to the wall on this one, hours spent but no clue what the problem is. I try to make two independent external calls via CompletableFuture. once both they complete I want to combine their results and return to the user.

On the logs I see first request is successfull but I get HTTP 503 error on the second request just on the line "restTemplate.postForEntity(..)"

Note: I do NOT use any Spring based @Async (or any Spring non blocking code) in my project.

Any idea? thx in advance

@Service
class MyService{

public Detail getResponse(){
    Executor exec = Executors.newCachedThreadPool();
    CompletableFuture<GenericResponse> c1 = CompletableFuture.supplyAsync(() -> myRestClient.getResponse(myRequestObject),exec);
    CompletableFuture<GenericResponse> c2 = CompletableFuture.supplyAsync(() -> myRestClient.getResponse(myRequestObject2),exec);
    return c1.thenCombine(c2, detailResponseMapper::mapDetail).join();
  }
}


@Component
class MyRestClient{

@Autowired
RestTemplate restTemplate;
 
private GenericResponse getResponse(MyRequest myRequest) {
    ResponseEntity<SofEnvelope> responseEntity = restTemplate.postForEntity(getUrl(myRequest.getPath()), getRequestEntity(myRequest), SofEnvelope.class);
    return new GenericResponse(responseEntity.getBody());
  }
}

And Error is

java.util.concurrent.CompletionException: org.springframework.web.client.HttpServerErrorException$ServiceUnavailable: 503 Service Unavailable

    at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)
    at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)
    at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1606)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.springframework.web.client.HttpServerErrorException$ServiceUnavailable: 503 Service Unavailable
    at org.springframework.web.client.HttpServerErrorException.create(HttpServerErrorException.java:85)

question from:https://stackoverflow.com/questions/65893201/completablefuture-error-httpservererror-503-service-unavailable

Answer 1

Waitting for answers