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From Rob Davies <rajdav...@gmail.com>
Subject Re: Deadlocks again :(
Date Thu, 18 Oct 2007 03:14:50 GMT
Thanks Nicky!

will apply patches asap - we're usually pretty good at avoiding  
deadlocks :(


cheers,

Rob

http://rajdavies.blogspot.com/



On Oct 17, 2007, at 10:40 PM, Nicky Sandhu wrote:

>
> Hi folks,
>  I got hit by another deadlock condition. Thats two different ones  
> on two
> consecutive days :(
>
> In ActiveMQ I see a lot of blocks of code using synchronized  
> access, nothing
> wrong with that but this increases the potential for deadlocks as  
> evidenced
> by the last two problems I have hit within the span of a couple of  
> days
> (https://issues.apache.org/activemq/browse/AMQ-1467,
> https://issues.apache.org/activemq/browse/AMQ-1468)
>
> This may be just my luck but I think it points to concurrency 101  
> lessons
> (http://undergraduate.csse.uwa.edu.au/units/CITS3213/lectures2/ 
> lect4.pdf)
> some which are a.) Lock on the appropriate object 2.) don't hold  
> locks for
> longer than absolutely necessary 3.) avoid nested locks like the  
> plague. 4.)
> Establish locking order for nested locks etc.
>
>  Thoughts?
>
> Nicky
>
> BTW. JConsole has a cool detect deadlock feature in jdk6 which  
> makes this
> exercise quick (once you stumble across the deadlock that is >:)) +  
> this
> article (http://www.javaspecialists.eu/archive/Issue130.html) has  
> code that
> you can run periodically to dump them when they happen... something  
> to be
> included in perhaps a debug version to help root all these out ?
> -- 
> View this message in context: http://www.nabble.com/Deadlocks-again- 
> %3A%28-tf4643498s2354.html#a13263508
> Sent from the ActiveMQ - Dev mailing list archive at Nabble.com.
>


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