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https://issues.apache.org/jira/browse/FLEX-34978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15031991#comment-15031991
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Douglas Yeager commented on FLEX-34978:
---------------------------------------
This is a good article on the subject at:
https://spring.io/blog/2015/04/03/how-spring-achieves-compatibility-with-java-6-7-and-8;
basically the recommendation is you need to cast the variable before accessing
the keySet() or just declare it appropriately.
> Shutdown errors when running Blazed DS inside of Tomcat & Java 8.
> -----------------------------------------------------------------
>
> Key: FLEX-34978
> URL: https://issues.apache.org/jira/browse/FLEX-34978
> Project: Apache Flex
> Issue Type: Bug
> Components: .Unspecified - Framework
> Affects Versions: BlazeDS 4.7
> Environment: Tomcat 7.0.58
> Java 8
> Reporter: Douglas Yeager
>
> Inside flex.messaging.FlexSessionManager a ConcurrentHashMap member variable
> is declared and later the keySet() is accessed. The ConcurrentHashMap
> interface has changed between Java 7 and Java 8. So although it will work
> when running with Java 7; it will break if you run with Java 8. It should be
> updated to declare the member as just a Map or ConcurrentMap (which is done
> elsewhere in the BlazeDS source); however, in the FlexSessionManager it is
> declared as:
> private final ConcurrentHashMap<Class<? extends FlexSession>,
> AbstractFlexSessionProvider> providers = new ConcurrentHashMap<Class<?
> extends FlexSession>, AbstractFlexSessionProvider>();
> Then in the FlexSessionManager.stop() implementation it performs the
> following directly off of the ConcurrentHashMap which results in a failure:
> /**
> * Stops the <tt>FlexSessionManager</tt>.
> * Any registered <tt>FlexSession</tt> providers are stopped and
> unregistered.
> */
> @Override
> public void stop()
> {
> if (!isStarted())
> return;
>
> super.stop();
>
> for (Class<? extends FlexSession> sessionClass : providers.keySet())
> {
> unregisterFlexSessionProvider(sessionClass);
> }
> providers.clear();
> }
> The following is the stacktrace seen in the error log on shutdown:
> 2015-11-25 13:47:01,804 [localhost-startStop-2] ERROR
> org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/context] -
> Servlet MessageBrokerServlet threw unload() exception
> javax.servlet.ServletException: Servlet.destroy() for servlet
> MessageBrokerServlet threw exception
> at
> org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1507)
> at
> org.apache.catalina.core.StandardWrapper.stopInternal(StandardWrapper.java:1847)
> at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
> at
> org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5707)
> at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
> at
> org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1591)
> at
> org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1580)
> at java.util.concurrent.FutureTask.run(FutureTask.java:262)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: java.lang.NoSuchMethodError:
> java.util.concurrent.ConcurrentHashMap.keySet()Ljava/util/concurrent/ConcurrentHashMap$KeySetView;
> at flex.messaging.FlexSessionManager.stop(FlexSessionManager.java:293)
> at flex.messaging.MessageBroker.stop(MessageBroker.java:380)
> at
> flex.messaging.MessageBrokerServlet.destroy(MessageBrokerServlet.java:263)
> at
> org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1486)
> ... 10 more
> There are two other classes that declare ConcurrentHashMap in the code that
> should be cleaned up too (although keySet() is not referenced in those
> classes , it would be better to address them to ensure this issue doesn't
> re-occur):
> flex.messaging.endpoints.BaseStreamingHTTPEndpoint
> flex.messaging.MessageBroker
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