anonymous wrote : 
  | I'm familiar with <check-valid-connection-sql>. The point of this 
exception-sorter exercise is to get away from the high expense of that 
approach. Ideally, we want to accept the cost of a single failure - followed by 
immediate invalidation of the pool - rather than the overhead of very frequent 
connection checks. 
  | 

There is no notion of a 'purge policy' in JBoss as this time where the pool is 
invalidated based on the error state of a *single* failing connection. There is 
some debate on including this for a future release.

JBoss 4.0.5 includes a background validation mechanism to evaluate pooled 
connections in the background rather than on retrieval which alleviates the 
overhead of constant validation. 

anonymous wrote : 
  | The distinction between XA errors and connection errors is an artifact of 
how the XA transactions are managed.
  | 

The difference is simply in the origin of the exception. XA based errors are 
reported from the underlying XA resource which don't currently have a hook to 
evaluate the error. Again, there is no reason why this couldn't be added.

As for the underlying MC being null, there are a few things that could cause 
this

1) The connection has been closed and you attempt to reuse the handle

2) The connection has been closed in another thread, and you attempt to reuse 
the handle

3) You are attempting to reuse the connection across method calls in an EJB and 
you do not have the spec compliant attribute set to true on the 
CachedConnectionManager (you would never really want to do this anyway).

4) You are not using connection validation and you have been given an invalid 
connection from the pool (this would be my guess). 

However, I am not seeing this in the stacktrace you posted. If the MC was 
actually null, you would never be able to execute a prepared statement, we 
check for this prior to every invocation to prohibit this behavior. I apologize 
if I am not looking in the right place. 






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