conflicts in database connections in JTA

[tbee]

I've got a setup where business model and Activiti are mixed into one engine. In order to facilitate transactional consistency, Bitronix JTA-XA is used to enabled distributed transactions. Configuration wise this works, however during the execution of a Activiti listener the connections have a conflict: the execution freezes and after a while a time out occurs. This looks very similar to a locking conflict.

In order to examine this, I've logged all changes that Activiti makes to the database:

 169: [EL Finer]: 2012-09-20 14:08:17.962–ClientSession(5578877)–Thread(Thread[main,5,main])–TX beginTransaction, status=STATUS_ACTIVE
 306: 2012-09-20 14:08:20,448 DEBUG #5958562[C22645161] activiti: execute: update ACT_GE_PROPERTY     …
 334: 2012-09-20 14:08:20,495 DEBUG #10522721[C5094311] activiti: execute: insert into ACT_RU_EXECUTION …
 360: 2012-09-20 14:08:20,495 DEBUG #25022548[C5094311] activiti: execute: insert into ACT_HI_PROCINST …
 384: 2012-09-20 14:08:20,511 DEBUG #13502571[C5094311] activiti: execute: insert into ACT_HI_ACTINST …
 408: 2012-09-20 14:08:20,526 DEBUG #25489800[C5094311] activiti: execute: insert into ACT_RU_VARIABLE …
 432: 2012-09-20 14:08:20,542 DEBUG #28968689[C5094311] activiti: execute: insert into ACT_RU_VARIABLE …
 456: 2012-09-20 14:08:20,542 DEBUG #9486511[C5094311] activiti: execute: insert into ACT_HI_ACTINST …
 486: 2012-09-20 14:08:20,557 DEBUG #4047039[C5094311] activiti: execute: insert into ACT_RU_TASK …
 520: 2012-09-20 14:08:20,573 DEBUG #2157445[C5094311] activiti: execute: insert into ACT_HI_TASKINST …
 534: 2012-09-20 14:08:20,589 DEBUG #22864626[C5094311] activiti: execute: insert into ACT_RU_IDENTITYLINK …
 674: [EL Finer]: 2012-09-20 14:08:20.714–UnitOfWork(30281720)–Thread(Thread[main,5,main])–TX afterCompletion callback, status=COMMITTED
 676: —————————
 677: [EL Finer]: 2012-09-20 14:08:20.729–ClientSession(5578877)–Thread(Thread[main,5,main])–TX beginTransaction, status=STATUS_ACTIVE
 741: 2012-09-20 14:08:20,808 DEBUG #17985579[C5094311] activiti: execute: update ACT_RU_TASK …
 769: 2012-09-20 14:08:20,823 DEBUG #32139235[C5094311] activiti: execute: update ACT_HI_TASKINST …
 781: 2012-09-20 14:08:20,823 DEBUG #28336320[C5094311] activiti: execute: update ACT_HI_ACTINST …
 877: 2012-09-20 14:08:20,901 DEBUG #28860947[C22645161] activiti: execute: insert into ACT_RU_VARIABLE …
 913: 2012-09-20 14:08:20,917 DEBUG #9528986[C5094311] activiti: execute: insert into ACT_RU_EXECUTION …
 937: 2012-09-20 14:08:20,933 DEBUG #33054865[C5094311] activiti: execute: insert into ACT_HI_ACTINST …
 961: 2012-09-20 14:08:20,948 DEBUG #21289936[C5094311] activiti: execute: insert into ACT_HI_ACTINST …
 991: 2012-09-20 14:08:20,980 DEBUG #23935686[C5094311] activiti: execute: insert into ACT_RU_TASK …
1025: 2012-09-20 14:08:20,995 DEBUG #31851612[C5094311] activiti: execute: insert into ACT_HI_TASKINST …
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Important is the number in square brackets which denotes the JDBC connection used. What I notice is that almost all interaction is done through [C5094311], except three which use [C22645161]. Now, prefix 408 and 432 and 877 use the same table through different connections. 877 is the result of this line:

      ProcessEngines.getDefaultProcessEngine().getRuntimeService().setVariable( getWorkflowProcessInstance().getProcessInstanceId(), "validateOfferStage", Long.valueOf(System.currentTimeMillis()));
‍‍‍

And indeed, if i comment this out, the executions continues. Why are there different database connections being used to write to the database?

[meyerd]

I wrote earlier:

Make sure to set
shareTransactionConnections=true

In https://jira.codehaus.org/secure/attachment/61422/BitronixTrial.java
you are missing the shareTransactionConnections=true have you added this in the meantime?

[tbee]

BTW, the essence of this code is attached to the Jira issue, so it should be fairly easy to reproduce.

@meyerd: sorry, I had not seen your reply yet. I will test that tomorrow!

[tbee]

That option does not exist.

Invalid property 'shareTransactionConnections' of bean class [org.activiti.engine.impl.cfg.StandaloneProcessEngineConfiguration]: Bean property 'shareTransactionConnections' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?

[meyerd]

Hi tbee,

it is not a property in activiti but a property on the Bitronix PoolingDataSource

[tbee]

Sorry. No difference. It's still using a different connection.

[tbee]

Let me take that back. Too many file and configurations running around. It seems to work. More testing…

[jbarrez]

That's great news. Please report back if it works, so future generations can learn from it.

@Daniel: thanks, didn't knew about that property!

[tbee]

I didn't either 🙂

But so far so good. I'm planning a blog post about this next week.

[jbarrez]

Awesome. Keep us posted!

[tbee]

Here is the blog:
http://tbeernot.wordpress.com/2012/10/02/stand-alone-business-model-with-activiti-eclipselink-and-un...