On Feb 23, 2011, at 7:35 PM, Kevan Miller wrote:

> 
> On Feb 22, 2011, at 4:37 PM, David Jencks wrote:
> 
>> cf 
>> https://issues.apache.org/jira/browse/GERONIMO-4576 
>> https://issues.apache.org/jira/browse/OPENEJB-1091 
>> 
>> For a long time we've known of this problem where an exception thrown by a 
>> transaction synchronization that causes a transaction to be marked for 
>> rollback only is lost.  When the user or openejb tries to commit the 
>> transaction the transaction manager throws a RollbackException which 
>> currently doesn't have any information about the original exception.
>> 
>> People have complained about this for a long time.... now we're trying to 
>> fix it.
>> 
>> There are two parts AFAICT.  I think in openejb we just need to take the 
>> TransactionRolledBackException we are currently throwing and call initCause 
>> with the RollbackException from the tm.  In TransactionPolicy this would be 
>> something like
>> 
>>       } catch (RollbackException e) {
>> 
>>           txLogger.info("The transaction has been rolled back rather than 
>> commited: " + e.getMessage());
>>           // TODO can't set initCause on a TransactionRolledbackException, 
>> update the convertException and related code to handle something else 
>>           Throwable txe = new 
>> javax.transaction.TransactionRolledbackException("Transaction was rolled 
>> back, presumably because setRollbackOnly was called during a 
>> synchronization: "+e.getMessage());
>> --            throw new ApplicationException(txe);
>> ++            throw new ApplicationException(txe.initCause(e);
>> 
>> In the transaction implementation we need to keep track of the exception 
>> that caused us to mark rollback only and then use it as the cause of the 
>> RollbackException, e.g.
>> 
>> private Exception markRollbackCause;
>> 
>> ...
>> RollbackException rollbackException = new RollbackException("Unable to 
>> commit: transaction marked for rollback");
>> if (markRollbackCause != null) { 
>> rollbackException.initCause(markRollbackCause); 
>> }
>> throw rollbackException; 
>> 
>> ...
>> 
>>   private void markRollbackCause(Exception e) {
>>       if (markRollbackCause == null) {
>>           markRollbackCause = e;
>>       }
>>   }
>> 
>> (this tm code is committed in rev 1073479 in my sandbox tm)
>> 
>> At the moment if a sync throws an exception, we keep calling the other 
>> syncs, and it would be possible for other ways of marking rollback only due 
>> to an exception to occur more than once as well.  So there's a question as 
>> to whether we should only record the first cause of rollback only or if we 
>> should keep track of a list of causes.  The code above only tracks the first 
>>  cause.  I'm really not sure what to think about this and would appreciate 
>> comments.
>> 
>> Thoughts?
> 
> Great to get more data captured. So, I'm all for it... 
> 
> Personally, I would think the *first* cause will almost always be the most 
> important information a user would want... Any situations where subsequent 
> exceptions are going to yield valuable information? Or will they mostly 
> generate noise?

Well, since the known cause of this problem is openjpa flushes during the tx 
syncs, it would be entirely possible to have more than one if there is more 
than one persistence unit/persistence context involved in the transaction. So 
I'd guess it's quite uncommon but entirely possible.  It's probably only an 
hour or so more work to implement something for more exception, dunno how much 
testing we'd want to do.

I don't know if there are likely to be additional "side effect" exceptions 
caused by a particular exception.  Offhand I can't think of any.

thanks
david jencks
 
> 
> --kevan

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