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From Tobia Conforto <>
Subject Re: Failing Mysql JDBC connections
Date Fri, 20 Jun 2008 08:25:45 GMT
I wrote:
> As soon as this happens, all pages being worked on at the same time  
> fail with such messages as:
> SQLTransformer.Query: Failed to execute query [...]
> com.mysql.jdbc.exceptions.MySQLNonTransientConnectionException: No  
> operations allowed after connection closed.

For the record, this was caused by a deadlock problem, where many  
simultaneous requests would get a connection for their SQLTransformer,  
exhausting the connection pool, and then get stuck requesting more  
connections through an input module I wrote myself, before the  
SQLTransformers had a chance to return the connections to the pool.

I worked around the problem by uncapping the database connections:

<pool-controller min="100" max="150" max-strict="false"/>

Now I'd like to know how to avoid the deadlock condition in the first  
place, with capped connections, but I'm not sure it can be done.  I've  
asked the dev list.


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