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From "Deepa Remesh (JIRA)" <derby-...@db.apache.org>
Subject [jira] Updated: (DERBY-1326) Network server may abandon sessions when Derby system is shutdown and this causes intermittent hangs in the client
Date Fri, 26 May 2006 16:56:31 GMT
     [ http://issues.apache.org/jira/browse/DERBY-1326?page=all ]

Deepa Remesh updated DERBY-1326:

    Attachment: sessionMgmt1_and_nosessionsforclosedthreads.diff

Hi Bryan,

I saw your question and suggestions in the previous comment while I was working on this new
combined patch. So this comment may sound off-base but I am just posting my thoughts. 

I was experimenting a bit with your patch and I think it is not the code that you added in
DRDAConnThread.run method which makes this new exception appear intstead of the old one. Reason
I say this is I modified your patch trying to see how we can avoid the closed_thread_getting_valid_session
scenario. In this patch, I removed the code you commented with //FIXME in DRDAConnThread.run.
Even after that, I see the same exception instead of the usual shutdown exception. However,
I have not figured out what is causing this new exception.

In the attached trial patch 'sessionMgmt1_and_nosessionsforclosedthreads.diff', I combined
your patches 'sessionMgmt1.diff' and 'no-sessions-for-closed-threads.diff'. To me, it looked
like 'sessionMgmt1.diff' solves all problems which we found except for closed_thread_getting_valid_session
scenario. This scenario seems to be solved by your previous patch 'no-sessions-for-closed-threads.diff'.
The problem which we found previously with 'no-sessions-for-closed-threads.diff' was that
the "createSession" was thinking there are freeThreads (freeThreads !=0 ). But actually the
threads it were thinking as available were already closed. For the combined patch to work,
freeThreads must become 0 after a restart. This is to ensure that a new thread is created
when a  new session comes in after a restart. I think the interrupt calls and the added synchronization
assure that freeThreads will become 0 before we start accepting new sessions. Does this sound

I have run the repro multiple times with this patch and did not see the hang.  If you think
this patch makes sense, can you please try it on the machine where you can repro the hang
easily to see if solves the hang? Thanks.

I will think more about your question and suggestions in the previous comment as I am planning
to look at DERBY-803/DERBY-1020 later today.

> Network server may abandon sessions when Derby system is shutdown and this causes intermittent
hangs in the client
> ------------------------------------------------------------------------------------------------------------------
>          Key: DERBY-1326
>          URL: http://issues.apache.org/jira/browse/DERBY-1326
>      Project: Derby
>         Type: Bug

>   Components: Network Server
>     Reporter: Deepa Remesh
>     Assignee: Bryan Pendleton
>  Attachments: repro1326.java, sessionMgmt1.diff, sessionMgmt1_and_nosessionsforclosedthreads.diff
> This issue was found when working on DERBY-1219. More details can be found in the comments
at http://issues.apache.org/jira/browse/DERBY-1219

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