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From "Bryan Pendleton (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1326) Network server may abandon sessions when Derby system is shutdown and this causes intermittent hangs in the client
Date Fri, 02 Jun 2006 18:55:31 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1326?page=comments#action_12414497 ] 

Bryan Pendleton commented on DERBY-1326:
----------------------------------------

Hi Deepa, thank you for the excellent analysis. It is very helpful.

The only part that troubles me is this:

> The interrupt calls and the added synchronization assure that freeThreads will 
> become 0 before we start accepting new sessions

I am not yet able to see why that is necessarily true.

I agree that we issue the interrupt() calls prior to completing the restart and prior
to accepting new sessions.

However, the thread which is interrupted responds to this interrupt asynchronously.

I believe that the only guarantee made by Java is that the thread which we are interrupting
will receive that interrupt some time in the future, but not necessarily immediately,
and not necessarily before we reach the end of the startNetworkServer() method
and declare the restart complete.

In practice, given that the startNetworkServer() method is going to unload the 
embedded engine, call System.gc(), and then reload the embedded engine,
that's probably enough work so that we have a very good chance that all the
old threads have received and responded to their interrupt() before we complete.

But I don't think it's actually *guaranteed* by the current changes in the combined patch.

I may be being too picky here. What do you think?


> 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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