[jira] [Created] (CXF-8022) Thread hangs using Reactor Flux when Exeption is Thrown

["KimJohn Quinn (JIRA)" <ji...@apache.org>]

KimJohn Quinn created CXF-8022:
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             Summary: Thread hangs using Reactor Flux when Exeption is Thrown
                 Key: CXF-8022
                 URL: https://issues.apache.org/jira/browse/CXF-8022
             Project: CXF
          Issue Type: Bug
          Components: JAX-RS
    Affects Versions: 3.3.1
         Environment: * JDK 11
 * CXF 3.3.1
 * Spring Boot (latest)
 * Undertow (latest)
 * Reactor (latest)
            Reporter: KimJohn Quinn


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. 


{code:java}
   @Path("/errors") 
   @Produces(APPLICATION_JSON) 
   public Flux<String> errors() 
   { 
       Flux<String> response =  Flux 
               .range(1, 5) 
               .flatMap(item-> 
               { 
                   if (item <=4) 
                   { 
                       return Mono.just("item: " + item); 
                   } 
                   else 
                   { 
                       System.out.println("---Hitting exception"); 
                       return Mono.error(new RuntimeException("runtime 
error")); 
                   } 
               }); 

       return response; 
   } {code}
 

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]



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