[Mulgara-general] Exception on startup

[David Moll]

The only exceptions on start-up that I've seen recently was when I
upgraded from v1.1.1 to v1.2.1 and started Mulgara up with the same
server1 directory.  Mulgara didn't fail to start, it just threw
exceptions about the block size being incorrect and then started up
normally.

Generally we also attempt to always shut Mulgara down by using the -x
switch on the jar file, instead of using ctrl-c in the console window.
I'm assuming that these two methods are similar as they both produce the
same message from Mulgara when used, but on production we don't have a
console available so the -x is sent to the jar file programmatically.

~Dave

-----Original Message-----
From: mulgara-general-bounces at mulgara.org
[mailto:mulgara-general-bounces at mulgara.org] On Behalf Of Andrae Muys
Sent: Thursday, April 24, 2008 11:54 AM
To: Mulgara General
Subject: Re: [Mulgara-general] Exception on startup


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  
> SVN
> 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

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



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