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You mention:
"It would be nice if the EJB vendors supplied a retry-on-deadlock parameter that would do this automatically with container-managed transactions. Without this automated feature, developers end up forcing EJB calls to use bean-managed transactions just to be able to retry on deadlocks. (One of the disadvantages to making your EJB calls use bean-managed transactions is that it's not obvious how to get the same semantics as a container-managed transaction with "RequiresNew" ...)"

Is BMT strictly required to retry? Suppose all business methods pass through an initial method with no transaction attributes. This method front_bizmethod() calls the actual business method which of course
has a transaction attribute of Required/RequiresNew etc.

public void front_bizmethod()
{
int retry_count = 0;
boolean retry = false;
do
{
try
{
bizmethod();
}
catch (RetryException re)
{
retry = true;
retry_count++;
}
} while (retry && retry_count < 10);
}

/** Business method -- has transaction attribute
* Required or RequiresNew
*/
bizmethod() throws RetryException
{
// Do business calls and throw a RetryException
// if a deadlock was detected by the database
}

What I mean is that there is a way around it by
coding an extra method.

What are your thoughts on the same ?

Thanks for this great article, Mike. I wasn't able to make it to JavaOne this year so I missed your BOF at JavaOne that looks like it was talking about this stuff (BOF-0534). Are there any slides from that that I can get ahold of?

With the power and simplicity that CMT (container managed transactions) brings, is there really no simple way to automatically handle database deadlock by retrying the transaction according to some given parameters (ie: number of retries, back off time, etc)? That would really be unfortunate.

Here are a few possible solutions, but they all seem sub-optimal for various reasons: (I would like to stay within the spec (EJB3/JEE5), but I'm not adament on this).

1) JBoss has a proprietary extension for this: (org.jboss.ejb.plugins.TxRetryExceptionHandler) However, besides being outside the spec, this implementation does not allow me to easily keep track of any state regarding the retry (ie: retry count numbers, data for back off algorithms, etc.).

2) I can use the EJB3 Interceptor spec, but this is really cumbersome because it ties in *after* the CMT stuff has already been setup.

3) I'm sure I could write a jboss-aop interceptor that would do the right thing here, but again it would be outside the spec. Has anyone done this already? I certainly don't want to reinvent the wheel on this one.

4) I could switch from CMT (container managed transactions) to BMT (bean managed transactions). This would give me more control over the the transaction endpoints but then I would have to give up all the niceties that CMT give me.

I really would like a nice solution for this...

Most non-trivial applications involve high degrees of concurrency and many layers of abstraction. Concurrency is associated with resource contention and an increase in deadlock conditions. The multiple layers of abstraction make it more difficult to isolate and fix the deadlock conditions.