Re: [Exist-open] track down failure

[Adam R. <ad...@ex...>]

Okay so firstly, which exact version of eXist-db are you using. When
you start eXist-db you should see an svn revision number mentioned in
the exist.log file.

Looking at the thread dump you sent through, you do indeed seem to
have several threads which are BLOCKED here -

org.exist.http.urlrewrite.XQueryURLRewrite.checkCache(XQueryURLRewrite.java:379)

They are attempting to synchronize on the urlCache, however this is
already in use by Thread P1-5 so they are waiting for Thread P1-5.

However Thread P1-5 seems to be waiting on a lock for the storage system -

org.exist.storage.lock.ReentrantReadWriteLock.acquire(ReentrantReadWriteLock.java:149)


So, if I have interpreted this correctly then yes there seems to be
some sort of thread locking issue occurring which you are seeing. I am
not sure if this is an issue that Wolfgang is already aware of or not?
He is really the master in this area as he built the URLRewrite stuff.


On 5 April 2011 17:03, Christian Meisenbichler
<chr...@mu...> wrote:
> I have found out how to get a thread dump. Please have a look (attachment).
> The server locked up. I don't know why. I cannot consciously reproduce the
> error. It just occurs every few hours.
>
> On Thu, Mar 31, 2011 at 1:44 PM, Wolfgang Meier <wol...@ex...>
> wrote:
>>
>> > Perhaps initially if you can get a thread dump and post it here for
>> > Wolfgang to see, that might help us see what is blocking what.
>>
>> The JMX client is able to report blocking locks within eXist if you
>> call it with option -l. Normally the output will be empty, which means
>> there are no blocking locks. Otherwise it will show you which thread
>> is waiting for which collection or resource lock. In combination with
>> a thread dump, this can really help to find out what's wrong.
>>
>> Wolfgang
>
>
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-- 
Adam Retter

eXist Developer
{ United Kingdom }
ad...@ex...
irc://irc.freenode.net/existdb