LRCO Technique with Narayana in Spring+Tomcat

[cijuj]

Hello,

I've a web application that I would like to run using Narayana Transaction Manager in a Spring environment. Our stack is:

Tomcat

Spring

Standalone Narayana TM

Hibernate

ActiveMQ

MariaDB Galera Cluster (No XA Support)

The article (https://developer.jboss.org/wiki/Spring32HornetQ2218JBossTS501Hibernate-XANon-XATransactionsWithConnectionPooling) really helped to understand and implement Narayana in a Spring + Tomcat environment.

The question I have is around the LRCO support. In my case, I have ActiveMQ that supports XA and a MariaDB Galera Cluster that doesn't support XA. Would Narayana automatically apply the LRCO technique in this case? If not, how do I get Narayana to do this.

With other standalone transaction managers like Bitronix/Atomikos, I could find LRC datasource wrappers which will take care of this. However I couldn't find any such wrappers for Narayana. It would be great if someone could point me to some examples that explains how to achieve LRCO in a Spring + Tomcat environment.

Thank you!

Ciju

[tomjenkinson]

Hi Ciju,

To be a last resource an XAResource (wrapper if necessary) just needs to implement LastResourceCommitOptimization (https://github.com/jbosstm/narayana/blob/master/ArjunaJTA/jta/classes/com/arjuna/ats/jta/resources/LastResourceCommitOptimisation.java) of Narayana.

To be sure its working, add your breakpoint here:

https://github.com/jbosstm/narayana/blob/master/ArjunaJTA/jta/classes/com/arjuna/ats/internal/jta/transaction/arjunacore/TransactionImple.java#L792

You will see we have an additional technique called commit markable resources too. This makes LRCO safer as by default it has the possibility for failure (it is described here: 11.3.2. About the LRCO Optimization for Single-phase Commit (1PC) )

Hope that helps,

Tom

[cijuj]

Thank you Tom. Do you have any sample/quick-start code in a Spring + Tomcat + Hibernate setup that I can use as a reference ?

Regards,

Ciju

[tomjenkinson]

I don't have a complete example but some of the techniques are illustrated here:

https://github.com/jbosstm/quickstart

However I would say that you won't find the LRCO example there. To make the XADS LRCO you could use the example you pointed to but manually wrap the PGXADataSource such that the getXAConnection::getXAResource that is returned implements our interface. Alternatively you could use IronJacamar (quickstart/jca-and-tomcat at master · jbosstm/quickstart · GitHub ) to get the DS as that can wrap with the right interface.

[cijuj]

Thanks Tom, that makes sense.

Now, I'm not sure if I'm doing the right thing. Since I'm using MariaDB connector, I just modified org.mariadb.jdbc.MariaXaResource (mariadb-connector-j/MariaXaResource.java at master · MariaDB/mariadb-connector-j · GitHub  to implement com.arjuna.ats.jta.resources.LastResourceCommitOptimisation instead of javax.transaction.xa.XAResource. I then get the following errors and warnings.

com.arjuna.ats.jta  - ARJUNA016061: TransactionImple.enlistResource - XAResource.start returned: XAException.XAER_RMFAIL for < formatId=131077, gtrid_length=29, bqual_length=36, tx_uid=0:ffffc0a81d7b:ce00:58475d90:c, node_name=1, branch_uid=0:ffffc0a81d7b:ce00:58475d90:e, subordinatenodename=null, eis_name=0 >

javax.transaction.xa.XAException

Error querying database.  Cause: java.sql.SQLException: Unable to enlist connection in transaction: enlistResource returns 'false'.

[tomjenkinson]

Sorry, my information was incomplete. The RMFAIL is because Galera likely won't take these XA directives. As you are already editing the source of Galera you could make further changes to prevent the XA calls ending up as XA directives on the driver.

Here is the IronJacamar XA wrapper for LastResources:

ironjacamar/LocalXAResourceImpl.java at 2e1ceded65fda57b4ef569d74ce920a079b794af · ironjacamar/ironjacamar · GitHub

You would really need to make all those changes, not just change the interface.

As you can see, things like xa_start are then mapped to the local transaction begin and so forth.

An alternative is to add the LRCO/CMR facility to transactional driver if you would be able to move to using that (normal XA example over here: quickstart/spring/jta at master · jbosstm/quickstart · GitHub ). If you would like me to investigate that let me know and I will see how feasible it would be.

I link to the docs for this item:

Narayana Product Documentation

[cijuj]

Thanks Tom. I'm yet to try it out. I'll keep you posted if I make any progress.

[tomjenkinson]

Thanks for the update - good luck!

[tomjenkinson]

Hi,

Just wondering how this went?

Thanks,

Tom