Re: [Jetty-support] ConcurrentModificationExceptions in AbstractSessionManager (Jetty 6.1.5)

[Silvio B. <sbi...@ja...>]

Hello Jan,

I got this trace from a customer and they have indeed not updated Jetty 
since 6.1.2. If I see this again I will come back to you.

Kind regards,

Silvio


Jan Bartel wrote:
> Hi Silvio,
>
> I can't imagine that a concurrent modification exception is ever a good thing,
> so it would be nice to track it down :-) It looks like the scavenger for expired
> sessions was trying to remove some sessions when maybe a new session was being
> inserted into the list. Looks like a synchronisation problem.
>
> However, the trace is not a lot of help because it looks more like a trace from 6.1.2 - 
> we haven't had a SessionScavenger thread since then (got replaced with a TimerTask
> instead). 
>
> The code has been worked on quite a bit since 6.1.2, so if you see the exception again 
> with 6.1.5 or 6.1.6, then please post again (or raise a bug) and we'll investigate.
>
> cheers
> Jan
>
>
> Silvio Bierman wrote:
>   
>> Hello all,
>>
>> I have seen these periodically in my system logs during the last two 
>> years. I am sure they where there when we used to run on Jetty5 but they 
>> still exist.
>>
>> Does anyone else see these? I have never experienced erratic server 
>> behavior related to these exceptions so I guess they are not a real problem?
>>
>> Kind regards,
>>
>> Silvio Bierman
>>
>>
>> 2007-10-15 19:45:59.075::WARN:  EXCEPTION
>> java.util.ConcurrentModificationException
>>        at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
>>        at java.util.HashMap$KeyIterator.next(Unknown Source)
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager$Session.invalidate(AbstractSessionManager.java:914) 
>>
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager.scavenge(AbstractSessionManager.java:468) 
>>
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager.access$600(AbstractSessionManager.java:62) 
>>
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager$SessionScavenger.run(AbstractSessionManager.java:1084) 
>>
>>        at 
>> org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475) 
>>
>> 2007-10-15 19:46:59.440::WARN:  EXCEPTION
>> java.util.ConcurrentModificationException
>>        at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
>>        at java.util.HashMap$KeyIterator.next(Unknown Source)
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager$Session.invalidate(AbstractSessionManager.java:914) 
>>
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager.scavenge(AbstractSessionManager.java:468) 
>>
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager.access$600(AbstractSessionManager.java:62) 
>>
>>        at 
>> org.mortbay.jetty.servlet.AbstractSessionManager$SessionScavenger.run(AbstractSessionManager.java:1084) 
>>
>>        at 
>> org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:475) 
>>
>>
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>
>
>