[jetty-discuss] [jira] Commented: (JETTY-515) Timer is missing scavenging Task in HashSessionManager

[Jan B. (JIRA) <ji...@co...>]

    [ http://jira.codehaus.org/browse/JETTY-515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_125368 ] 

Jan Bartel commented on JETTY-515:
----------------------------------

Dimitry,

Also, were there any exceptions in the log files?


Jan

> Timer is missing scavenging Task in HashSessionManager
> ------------------------------------------------------
>
>                 Key: JETTY-515
>                 URL: http://jira.codehaus.org/browse/JETTY-515
>             Project: Jetty
>          Issue Type: Bug
>          Components: Servlet
>    Affects Versions: 6.1.7
>         Environment: Windows Server 2003, jdk1.6.0, jetty 6.1.7
>            Reporter: Dimitry D'hondt
>            Assignee: Jan Bartel
>         Attachments: scavenge.jpg
>
>
> Sporadically our production environment goes out of Heap, because expired sessions are not scavenged.
> To validate this we have performed a heap dump when the server is hitting its maximum heap usage, before crashing the server.
> In this .hprof heap dump we used SAP Memory Analyzer to do post-mortem analysis. (screenshot of problem in attachment)
> What happens is that somehow the java.util.Timer object (_timer in the HashSessionManager) ends up not having any TimerTask assigned to it (we are absolutely sure about this - in other heap dumps the TimerTask is clearly there - pointing to the anonymous inner class that calls the scavenge() method).
> Hence timed-out sessions are not garbage collected as they remain referenced through the SessionManager.
> Analyzing the Session objects in the heap dump reveals a very large amount of HashSessionManager$$Session objects (about 10 times more then normal system usage). Ffurthermore the oldest Session objects have lastAccessed times that were more than 24 hours before the system heap problems.
> Often the system can run weeks before experiencing this problem.
> If more information is needed please contact me at dimitry_dhondt [at] yahoo.com
> Dimitry.

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