[jbossts-issues] [JBoss JIRA] Commented: (JBTM-354) race condition in XAResource start/end handling due to async rollback

[Mark Little (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBTM-354?page=comments#action_12408882 ] 
            
Mark Little commented on JBTM-354:
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The best way to do this would be to resurrect BasicAction criticalStart and criticalEnd because this race condition will show up elsewhere (e.g., registering a synchronization "just as" the transaction times out).

> race condition in XAResource start/end handling due to async rollback
> ---------------------------------------------------------------------
>
>                 Key: JBTM-354
>                 URL: http://jira.jboss.com/jira/browse/JBTM-354
>             Project: JBoss Transaction Manager
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: JTA Implementation, JTS Implementation
>    Affects Versions: 4.3.0.GA, 4.2.3.SP5
>            Reporter: Jonathan Halliday
>         Assigned To: Jonathan Halliday
>             Fix For: 4.2.3.SP8, 4.4.CR1
>
>
> There exists a race condition such that we may call start on an XAResource but never call end (or anything else) on it if the transaction times out whilst the resource enlistment is still in progress. This is a Bad Thing and may make resource managers unhappy.
> To reproduce:
>         TransactionManager tm = new TransactionManagerImple();
>         tm.setTransactionTimeout(5);
>         tm.begin();
>         Transaction t = tm.getTransaction();
>         // XAResourceImpl has a start method with Thread.sleep longer than 5s
>         XAResource xaResource = new XAResourceImpl(); 
>         t.enlistResource(xaResource);
>         Thread.sleep(10);
>         // reaper times out the tx, resource manager for XAResource
>         // *may* have received start but never receives end.
> Fix notes: TransactionImple.enlistResource needs to lock out the reaper thread.  At first glance an alternative fix is to put the resource into the transaction's internal data structure before calling start on it, but that would allow an 'end, begin' sequence of calls to be seen by the resource manager.
> caution: ref support case i-t #171373 there *may* exist additional race conditions in the app server JCA so this change alone won't necessarily fix the problem.

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