[jira] Commented: (WW-2985) ExecuteAndWaitInterceptor puts non-serializable object on the session

["Wes Wannemacher (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/struts/browse/WW-2985?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=46056#action_46056 ] 

Wes Wannemacher commented on WW-2985:
-------------------------------------

I think the problem may be more complicated than I thought when I first read this issue. When the "long-running" action is placed in the session, it is backgrounded as a thread. I don't see how another server would be able to grab the thread and continue executing it... I would think that any actions needing to use the ExecuteAndWaitInterceptor need to remain on one server. There is another issue that I linked this one too because the same object being unserializable means that the TokenSessionStoreInterceptor can't work in a cluster. 

I don't have a cluster handy to play around with this, but I would think that your solution wouldn't really work, as you said, since a running thread isn't going to easily serialize. 

> ExecuteAndWaitInterceptor puts non-serializable object on the session
> ---------------------------------------------------------------------
>
>                 Key: WW-2985
>                 URL: https://issues.apache.org/struts/browse/WW-2985
>             Project: Struts 2
>          Issue Type: Bug
>          Components: Core Interceptors
>    Affects Versions: 2.1.6
>         Environment: All
>            Reporter: Brian Levine
>            Priority: Critical
>
> Using ExecuteAndWaitInterceptor puts StrutsRequestWrapper on the session. This causes a NotSerializable exception in Tomcat (and I suppose other app servers) when session serialization for clustering is enabled.
> The problem appears to be a member variable in BackgroundProcess which contains a reference to StrutsRequestWrapper in its object containment hierarchy.
> The result of this bug is that no session data is replicated when an action using the ExecuteAndWaitInterceptor is invoked.  It should also be noted that BackgroundProcess (the class that is actually added to the session) contains a reference to ActionInvocation which can result in quite a bit of data being added to the session. This should be stripped down so that only the absolute minimum information necessary to execute the action is added to BackgroundProcess.
> Temporary workaround:
> I created my own subclass of ExecuteAndWaitInterceptor and overrode getNewBackgroundProcess to return my own implementation of BackgroundProcess in which the two suspect member variables are declared transient.  This at least fixes the NotSerializableException although there is still a window of vulnerability if one node in a cluster goes down while the application is in the middle of an action that uses the ExecuteAndWaitInterceptor.
> See also: WW-2803 

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