JTA transaction manager – Atomikos or Bitronix?

Recently I was faced with a problem of choosing an appropriate transaction manager for one of our server-side applications.

Transaction manager requirements:

• JTA compliant
• integrates with Spring
• open-source and free
• support of several different resources: Postgresql with pooled connections, ActiveMQ (JMS), XADisk (filesystem)
• easy usage
• one-phase commit optimization

With the exception of XADisk, these are pretty common requirements.

Doing a little searching, I’ve found following transaction managers:

• Atomikos
• Bitronix
• JBoss Transactions
• JOTM

The first three seemed worth a try. Last one looks like a dead project and I do not like it.

Finally, I ended up with Bitronix, but it wasn’t easy to choose.

Atomikos

Firstly I tried Atomikos. Seemed most mature and well documented. Unfortunately, it is NOT that mature. Let’s look at major problems I was facing with Atomikos.

1) Poor logging and exception handling:

• In some cases, Atomikos incorrectly reported (swallowed) exceptions coming from Postgresql in prepare phase of two-phase commit. Only some general purpose exception was logged and it was impossible to find a true cause of the error in the log. This issue is generally related to poor exception handling in Atomikos.
• Message log levels are insane. Atomikos logs quite a lot of messages on INFO and WARN level. This is not a big deal, but it is annoying and inconsistent with a common usage of log levels.
• Bug: without any apparent reason this message is  often logged: WARN atomikos – Forcing close of pending statement: Pooled statement wrapping physical statement null
• Unclear logging configuration

2) Disabled support for one-phase commit optimization:

• even if the transaction works with a single resource, the two-phase commit is always used
• there is a note in the Atomikos source code saying that this behaviour is a consequence of some unrelated bug-fix

Despite all of this, I managed to use Atomikos and it worked. But I’ve been somehow disappointed with all that small problems. So I decided to try Bitronix.

Bitronix

It works in a similar manner like Atomikos. The only difference is that Bitronix does not support XADisk out-of-the-box. I had to do a little programming to get it working. After that, Bitronix works very well and does not suffer with any of the Atomikos’s issues. I am simply satisfied.

Bitronix and XADisk

XADisk documentation contains a brief description of how to enable XADisk in JTA environment.

To make it work with Bitronix, you need to do a little bit more. Here is  what I have done.

1) Implement two new classes:

• Create a new implementation of interface XAResourceProducer for XADisk – take Ehcache implementation and just copy/rename it
  • class name: XaDiskResourceProducer
• Similarly – create a new implementation of  XAResourceHolder from Ehcache version
  • class name: XaDiskXAResourceHolder
• (edit: Dec 04, 2011) As a last step, I’ve modified a small part of the XaDiskResourceProducer to ensure proper registering/unregistering of the resources (methods registerXAResource and unregisterXAResource)

Look at my clasess: bitronix-xadisk-v2 (edit: Dec 04, 2011)

2) For every transaction where you need an XADisk session you must follow these steps:

• Register XADisk’s XAResource into Bitronix using static method registerXAResource() on your XAResourceProducer implementation
• Enlist XADisk’s XAResource into every transaction where you are using XADisk
• Unregister XADisk’s XAResource from Bitronix

My solution:

XASession xaSession = xaFileSystem.createSessionForXATransaction();
final XAResource xaResource = xaSession.getXAResource();
XaDiskResourceProducer.registerXAResource( "MAIN", xaResource );
transaction.enlistResource( xaResource );
transaction.registerSynchronization( new Synchronization() {

  @Override
  public void beforeCompletion() {
  }

  @Override
  public void afterCompletion( int status ) {
    XaDiskResourceProducer.unregisterXAResource( "MAIN", xaResource );
  }
} );

JBoss Transactions

I gave it only a few minutes and have no real experience with it. Its documentation is kind of old-school and hard to use.

Conclusion

Bitronix met 100% of our requirements. Despite its design-less web site, it’s usable and easy to configure. Its source code looks much better than that of Atomikos. I simply trust it more.

Bitronix works well with Postgresql and is extensible to allow usage of XADisk for filesystem transactions. This is what I tried so far.

We don’t have Bitronix deployed in a production environment yet, so I have no production use experience. Especially I have not tested its ability to work with JMS – I will add this part as soon as I get to it.

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