From: Magnus Blåudd
Date: November 26 2012 3:30pm
Subject: Re: Problem with multithreading and ClusterJ
List-Archive: http://lists.mysql.com/cluster/8436
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On Mon 26 Nov 2012 04:09:42 PM CET, Graeme Wallace wrote:
> I'm trying to make my app multi-threaded and running into
> problems.
>
> I have a Session local to each thread that is attempting to write to the
> db. I'm batching up many savePersistent() calls in a transaction - but when
> the transaction commits I invariably end up with
>
> Nov 21, 2012 7:22:29 PM com.mysql.clusterj.tie.Utility throwError
> SEVERE: Error in NdbJTie: returnCode -1, code 266, mysqlCode 146, status 1,
> classification 10, message Time-out in NDB, probably caused by deadlock .
>
> For reading the docs, it looks like there shouldn't be table locking going
> on - so i dont understand what resource is being held by one thread that
> stops the others from being able to write at the same time.
>
> Any clues would be most helpful,
>
> regards,
>
>
> Graeme
>

Check out Matthew's reply in in this forum thread 
http://forums.mysql.com/read.php?25,505712,505757

"Due to the distributed nature of NDBCLUSTER there is no automatic 
deadlock detection mechanism within the NDBCLUSTER engine. The only 
indication that the cluster gives that there is a *possible* deadlock 
is the "Lock wait timeout exceeded". This error occurs when a given 
lock operation takes longer than TransactionDeadlockDetectionTimeout 
(default 1200 ms.). If you have large transactions that lock many rows 
at once or if you have long running transactions these can prevent this 
or transactions from completing quickly. Try to avoid large or long 
running transactions by breaking them into smaller chunks. The 
TransactionDeadlockDetectionTimeout can also be reached when a node is 
overloaded but has not yet been ejected from the cluster for missing 
heartbeats longer than 4xHeartbeatIntervalDbDb (default 1500 ms. each). 
"

/ Magnus