[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
> 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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