Bug 54507 - Notification for expired session sent to still initializing servlet context
Notification for expired session sent to still initializing servlet context
Status: RESOLVED FIXED
Product: Tomcat 7
Classification: Unclassified
Component: Catalina
7.0.33
PC Linux
: P2 normal (vote)
: ---
Assigned To: Tomcat Developers Mailing List
:
Depends on:
Blocks:
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Reported: 2013-01-31 07:59 UTC by boschman
Modified: 2013-02-01 12:23 UTC (History)
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Description boschman 2013-01-31 07:59:11 UTC
The Tomcat backgroundprocess for expiring sessions does not wait for the servlet context (application loaded by a filter) to be fully initialized. The following stacktrace happens while Filter.init is still being executed (hence the application is only partly initialized and shouldn't receive any work):

        at org.apache.wicket.protocol.http.WebApplication.sessionUnbound(WebApplication.java:552)
        at org.apache.wicket.session.HttpSessionStore$SessionBindingListener.valueUnbound(HttpSessionStore.java:465)
        at org.apache.catalina.session.StandardSession.removeAttributeInternal(StandardSession.java:1800)
        at org.apache.catalina.session.StandardSession.expire(StandardSession.java:865)
        at org.apache.catalina.session.StandardSession.isValid(StandardSession.java:658)
        at org.apache.catalina.session.ManagerBase.processExpires(ManagerBase.java:534)
        at org.apache.catalina.session.ManagerBase.backgroundProcess(ManagerBase.java:519)
        at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1352)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1530)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1540)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1540)
        at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1519)
        at java.lang.Thread.run(Thread.java:722)
Comment 1 Mark Thomas 2013-02-01 12:23:27 UTC
Configuring an application in a Filter.init() method is a poor design choice. Application initialization should happen in a ServletContextListener.

There is a little ambiguity in section 6.2.1 of the Servlet specification but your interpretation (that Filter#init() must be called for all filters before requests are served) is consistent with how the Tomcat developers have implemented filter initialization.

That said, I do not see how the behavior you describe can occur. The background processing method exits immediately if the component is not available - which it isn't when the Filters are being started.

I have moved the starting/stopping of the thread since the thread can't do anything until the start method completes so there is no point starting it earlier. However, that shouldn't change the current behavior.

I also found and fixed a problem in Tomcat trunk where the test for component availability was being skipped. However, Tomcat 7 does not exhibit that problem.

Marking this as fixed due to the Tomcat 8 fix.