[jira] [Commented] (FLEX-34978) Shutdown errors when running Blazed DS inside of Tomcat & Java 8.

["Douglas Yeager (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLEX-34978?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15031991#comment-15031991 ] 

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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