Reactive Feign with Webflux

Question

I'm using Reactive Feign implementation from here (https://github.com/Playtika/feign-reactive) but even when I tried to use Spring WebClient I have the same problem.

When I call a URL with a POST Request, passing a JSON Body, the stream never done. The thread remains freeze awaiting for finish and it never hapens.

fun post(request: PostRequest): Mono<PostResponse> {   
    val response = myClient.post(request)
        .onErrorResume {
            log.error("Error sending request", it)
            Mono.error<PostResponse>(it)
        }
        .doOnSuccess {
            log.info("Success with response $it")
            it
        }
    response.block() 
    return response
}

But, when I call subscribe() nothing happens and request remains freezed. When I call block() method, it throws the follow exception:

java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-4

Running Debug, I got this log:

2021-01-06 11:57:42.047 DEBUG 13624 --- [ctor-http-nio-4] r.client.log.DefaultReactiveLogger       : [MyClient#post]--->POST http://localhost:8081/post HTTP/1.1
2021-01-06 11:57:42.048 DEBUG 13624 --- [ctor-http-nio-4] r.n.resources.PooledConnectionProvider   : [id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80] Channel acquired, now 1 active connections and 0 inactive connections
2021-01-06 11:57:42.048 DEBUG 13624 --- [ctor-http-nio-4] reactor.netty.ReactorNetty               : [id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80] Added decoder [ReadTimeoutHandler] at the end of the user pipeline, full pipeline: [reactor.left.httpCodec, ReadTimeoutHandler, reactor.right.reactiveBridge, DefaultChannelPipeline$TailContext#0]
2021-01-06 11:57:42.048 DEBUG 13624 --- [ctor-http-nio-4] reactor.netty.ReactorNetty               : [id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80] Added decoder [WriteTimeoutHandler] at the end of the user pipeline, full pipeline: [reactor.left.httpCodec, ReadTimeoutHandler, WriteTimeoutHandler, reactor.right.reactiveBridge, DefaultChannelPipeline$TailContext#0]
2021-01-06 11:57:42.048 DEBUG 13624 --- [ctor-http-nio-4] r.netty.http.client.HttpClientConnect    : [id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80] Handler is being applied: {uri=http://localhost:8081/post, method=POST}
2021-01-06 11:57:42.049 DEBUG 13624 --- [ctor-http-nio-4] r.n.resources.PooledConnectionProvider   : [id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80] onStateChange(POST{uri=/post, connection=PooledConnection{channel=[id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80]}}, [request_prepared])
2021-01-06 11:57:42.074 DEBUG 13624 --- [ctor-http-nio-4] r.n.resources.PooledConnectionProvider   : [id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80] onStateChange(POST{uri=/post, connection=PooledConnection{channel=[id: 0x77f83c34, L:/10.7.8.88:62005 - R:localhost/127.0.0.1:80]}}, [request_sent])

There is a way to make this request?

you are not allowed to block in webflux applications, that defeats the entire purpose of using a NON-BLOCKING framework like Webflux. — Toerktumlare, Jan 06 '21 at 16:49
@Toerktumlare But without block(), the service never respond success or error.. How can I recreate this request with Spring WebClient?? I tried, but same result — Efraim Coutinho, Jan 06 '21 at 18:07
well i can't answer that i have never used `feign-reactive` and you have posted minimal code, so your question is non reproducible and impossible to answer. If it freezes, it could be your network, but as said, no one can answer this becuase it is non reproducible. — Toerktumlare, Jan 06 '21 at 18:11

score 2 · Answer 1 · answered Jan 09 '21 at 18:13

Replace .block() call by .map() in this way:

fun post(request: PostRequest): Mono<PostResponse> =
    myClient.post(request)
        .onErrorResume {
            log.error("Error sending request", it)
            Mono.error<PostResponse>(it)
        }
        .map {
          log.info("Success with response $it")
          ok(it)
        }

.map() is synchronous, so it does the same as subscribe(). Subscribe should be called from the client-side, not from the server-side on non-blocking pipelines. With .map() you the pipeline becomes synchronous, but it won't run until a client .subscribes()

Reactive Feign with Webflux

1 Answers1