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  1. CXF
  2. CXF-8022

Thread hangs using Reactor Flux when Exeption is Thrown



    • Bug
    • Status: Closed
    • Blocker
    • Resolution: Fixed
    • 3.2.8, 3.3.1
    • 3.2.9, 3.3.2
    • JAX-RS
      • JDK 11
      • CXF 3.3.1
      • Spring Boot (latest)
      • Undertow (latest)
      • Reactor (latest)
    • Unknown
    • Important


      We have run into a serious issue that was not expected or caught until late 
      it appears with CXF and Reactor in Undertow (using Spring Boot)... 

      The Flux throws an exception inside and hangs infinitely, requiring the 
      process to be forcibly killed (kill -9).   

      We are using Spring Boot (latest), CXF (latest) with Reactor extension, 
      Undertow and Reactor.  Has anyone run into this and are there or could there 
      be any potential work around to handle this?

      We wanted to stick with using CXF for both our standard REST resources and Reactor resources because CXF has always worked well for us plus we are using the OpenAPI swagger integration.  Not being able to resolve this or have an established workaround may cause us to have to completely revert to Spring controllers.

      There seems to be a problem with the onComplete handling of Fluxes when it 
      throws a RuntimeException.  Basically, if you try to the endpoint, it will 
      hang.  I've tracked it down to the writeTo function in 
      StreamingAsyncSubscriber where the queue is empty but "completed" is still 
      false so it goes into an infinite loop.  You can repeat it by running the 
      code below. 

         public Flux<String> errors() 
             Flux<String> response =  Flux 
                     .range(1, 5) 
                         if (item <=4) 
                             return Mono.just("item: " + item); 
                             System.out.println("---Hitting exception"); 
                             return Mono.error(new RuntimeException("runtime 
             return response; 


      I also posted this on the forums hoping someone can assist - http://cxf.547215.n5.nabble.com/Thread-hangs-when-using-reactor-cxf-and-undertow-td5796369.html


      The log output, up until manually killing the process looks like:

      [DEBUG] o.a.c.j.interceptor.JAXRSInInterceptor : Found operation: errors
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Invoking handleMessage on interceptor org.apache.cxf.interceptor.OneWayProcessorIntercep tor@6e760b48
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Invoking handleMessage on interceptor org.apache.cxf.interceptor.ServiceInvokerIntercept or@6d7702a0
      [DEBUG] o.a.cxf.service.invoker.AbstractInvoker : Invoking method public reactor.core.publisher.Flux io.logicdrop.drools.endpoints.DroolsR ulesetResource.errors() on object io.logicdrop.drools.endpoints.DroolsRulesetResource@23718909 with params [].
      [DEBUG] reactor.util.Loggers$LoggerFactory : Using Slf4j logging framework
      ---Hitting exception
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Invoking handleMessage on interceptor org.apache.cxf.interceptor.OutgoingChainIntercepto r@308be65a
      [DEBUG] o.a.c.i.OutgoingChainInterceptor : Interceptors contributed by bus: []
      [DEBUG] o.a.c.i.OutgoingChainInterceptor : Interceptors contributed by service: []
      [DEBUG] o.a.c.i.OutgoingChainInterceptor : Interceptors contributed by endpoint: [org.apache.cxf.interceptor.MessageSenderIntercept or@3f0061c3]
      [DEBUG] o.a.c.i.OutgoingChainInterceptor : Interceptors contributed by binding: [org.apache.cxf.jaxrs.interceptor.JAXRSOutIntercept or@5419dbea]
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Adding interceptor org.apache.cxf.interceptor.MessageSenderInterceptor@3f0061c3 to phase prepare-send
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Adding interceptor org.apache.cxf.jaxrs.interceptor.JAXRSOutInterceptor@5419dbea to phas e marshal
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Chain org.apache.cxf.phase.PhaseInterceptorChain@63b5b52 was created. Current flow:
      prepare-send [MessageSenderInterceptor]
      marshal [JAXRSOutInterceptor]

      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Invoking handleMessage on interceptor org.apache.cxf.interceptor.MessageSenderIntercepto r@3f0061c3
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Adding interceptor org.apache.cxf.interceptor.MessageSenderInterceptor$MessageSenderEndi ngInterceptor@30cf09f to phase prepare-send-ending
      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Chain org.apache.cxf.phase.PhaseInterceptorChain@63b5b52 was modified. Current flow:
      prepare-send [MessageSenderInterceptor]
      marshal [JAXRSOutInterceptor]
      prepare-send-ending [MessageSenderEndingInterceptor]

      [DEBUG] o.apache.cxf.phase.PhaseInterceptorChain : Invoking handleMessage on interceptor org.apache.cxf.jaxrs.interceptor.JAXRSOutIntercept or@5419dbea
      [DEBUG] o.a.c.j.interceptor.JAXRSOutInterceptor : Response content type is: application/json
      [DEBUG] o.apache.cxf.ws.addressing.ContextUtils : retrieving MAPs from context property javax.xml.ws.addressing.context.inbound
      [DEBUG] o.apache.cxf.ws.addressing.ContextUtils : WS-Addressing - failed to retrieve Message Addressing Properties from context

      Same scenario with a Mono appears to show the stream "completing"...


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              reta Andriy Redko
              kjq KimJohn Quinn
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