NoSuchMethodError com.netflix.zuul.context.RequestContext.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;

[esteveblanch]

Hello,

I am using zuul-core 1.3.0 with Spring-Cloud in a JDK 1.7 environment.
I started getting a strange error when executing zuul:

com.netflix.zuul.exception.ZuulException: Filter threw Exception
	at com.netflix.zuul.FilterProcessor.processZuulFilter(FilterProcessor.java:227) [zuul-core-1.3.0.jar:1.3.0]
	at com.netflix.zuul.FilterProcessor.runFilters(FilterProcessor.java:157) [zuul-core-1.3.0.jar:1.3.0]
	at com.netflix.zuul.FilterProcessor.preRoute(FilterProcessor.java:133) [zuul-core-1.3.0.jar:1.3.0]
	at com.netflix.zuul.ZuulRunner.preRoute(ZuulRunner.java:105) [zuul-core-1.3.0.jar:1.3.0]
	at com.netflix.zuul.http.ZuulServlet.preRoute(ZuulServlet.java:125) [zuul-core-1.3.0.jar:1.3.0]
	at com.netflix.zuul.http.ZuulServlet.service(ZuulServlet.java:74) [zuul-core-1.3.0.jar:1.3.0]
	at org.springframework.web.servlet.mvc.ServletWrappingController.handleRequestInternal(ServletWrappingController.java:157) [spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
	at org.springframework.cloud.netflix.zuul.web.ZuulController.handleRequest(ZuulController.java:44) [spring-cloud-netflix-core-1.4.3.RELEASE.jar:1.4.3.RELEASE]
	at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:50) [spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) [spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) [spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) [spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) [spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:624) [tomcat-embed-core-7.0.81.jar:7.0.81]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) [spring-webmvc-4.3.12.RELEASE.jar:4.3.12.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) [tomcat-embed-core-7.0.81.jar:7.0.81]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) [tomcat-embed-core-7.0.81.jar:7.0.81]
..........
Caused by: java.lang.NoSuchMethodError: com.netflix.zuul.context.RequestContext.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;
	at com.netflix.zuul.context.RequestContext.copy(RequestContext.java:546) ~[zuul-core-1.3.0.jar:1.3.0]
	at com.netflix.zuul.FilterProcessor.processZuulFilter(FilterProcessor.java:190) ~[zuul-core-1.3.0.jar:1.3.0]
	... 109 more

Apparently it seems all ok, but, after some hours of investigation, i arrived at this gist: https://gist.github.com/AlainODea/1375759b8720a3f9f094

Basically it says that the method keySet() in ConcurrentHashMap, has different return type in JDK 1.7 and JDK 1.8. In JDK 1.7, it returns a Set and in JDK 1.8 it returns a KeySetView.

It my be possible that if you compile code using JDK 1.8, but with compatibility with JDK 1.7, this kind of errors may rise.

I checked that jar artifacts deployed on maven central, are compiled with JDK 1.8, and if you see the staktrace, the code specs a KeySetView.

I decompiled the source code of the jar, and if we inspect the bytecode of the RequestContext in the method copy():

         L9 {
             aload0 // reference to self
             invokevirtual com/netflix/zuul/context/RequestContext keySet(()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;);
             invokevirtual java/util/concurrent/ConcurrentHashMap$KeySetView iterator(()Ljava/util/Iterator;);
             astore2
         }

Effectively appears a reference to KeySetView, that does not exists in JDK 1.7.

The immediate solution to this problem, is compile the source code using JDK 1.7, and not using JDK 1.8.

I will try this to check if effectively compiling zuul with JDK 1.7 solves this problem.

[esteveblanch]

I downloaded the source code of zuul-core 1.3.0 and I compiled using the JDK 1.7.

The decompiled bycode source now is different and there is no reference to KeySetView:

         L9 {
             aload0 // reference to self
             invokevirtual com/netflix/zuul/context/RequestContext keySet(()Ljava/util/Set;);
             invokeinterface java/util/Set iterator(()Ljava/util/Iterator;);
             astore2
         }

I added the jar compiled with JDK 1.7 to my application, and the exception does not appears any more, and it works as expected.

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