[Mulgara-general] Exception on startup

Andrae Muys andrae at netymon.com
Thu Apr 24 15:53:36 UTC 2008

On 25/04/2008, at 1:49 AM, Alex Hall wrote:
> Paul Gearon wrote:
>> On Wed, Apr 23, 2008 at 6:41 PM, jopaki <jopaki at gmail.com> wrote:
>>> Paul,
>>> Thanks for the reply.  It was in fact a 'dirty' shutdown.  I'm  
>>> guessing i
>>> didn't ensure all jvm processes were destroyed before my attempt  
>>> to re-start
>>> mulgara.
>> Hmmm, that means that two JVMs may have been trying to map the same
>> file at the same time. Given the exception, I'm guessing this was
>> working when it was all read-only, but it failed when it tried to
>> force a write.
> I have been seeing this same exception today, running Windows as well.
> Actually, I saw it a week or two ago when restarting after Mulgara was
> accidentally killed during startup.  But I've seen it multiple times
> today, including once right after I booted the machine and I *know*
> there were no other JVM's trying to map the file at the same time.   
> The
> server eventually starts successfully, but sometimes it's necessary to
> try multiple times before it does.  It's odd that the issue would rear
> its head at this time, however, since the latest updates I got from  
> were localized in the TQL interpreter.
> What exactly do you mean by a clean shutdown?  I thought that the
> philosophy on shutdowns was that killing the Java process (i.e.  
> hitting
> Ctrl-C) is considered a clean shutdown, as care is taken during
> transactions to ensure that the system can always be restored to a
> consistent state.  Is this not the case?

It is the case.  However if mulgara is given the opportunity it will  
explicitly release any operating-system resources, including any  
locks or open files.  I suspect what is happening here is that  
windows is taking its time cleaning up after the process, and we are  
conflicting with a stale lock of some description.  But that really  
is just a wild guess.


Andrae Muys
andrae at netymon.com
Senior RDF/Semantic-Web Consultant
Netymon Pty Ltd

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