Transactions enhancements in 5.0

Besides other cool features such as Map reduce and distributed executors, Infinispan 5.0.0 "Pagoa" brings some significant improvements around transactional functionality:

• transaction recovery is now supported, with a set of tools that allow state reconciliation in case the transaction fails during 2nd phase of 2PC. This is especially useful in the case of transactions spreading over Infinispan and another resource manager, e.g. a database (distributed transactions). You can find out more on how to enable and use transaction recovery here.
• Synchronization enlistment is another important feature in this release. This allows Infinispan to enlist in a transaction as an Synchronization rather than an XAResource.This enlistment allows the TransactionManager to optimize 2PC with a 1PC where only one other resource is enlisted with that transaction (last resource commit optimization). This is particularly important when using Infinispan as a 2nd level cache in Hibernate. You can read more about this feature here.
• besides that several bugs were fixed particularly when it comes to the integration with a transaction manager - BIG thanks to the community for reporting and testing them!

To summarise, Infinispan can participate in a transaction in 3 ways:

1. as a fully fledged XAResource that supports recovery
2. as an XAResource, but without recovery. This is the default configuration
3. and as an Synchronization

In order to analyze the performance of running Infinispan in different transactional modes I've enhanced and used Radargun. The diagram below shows a performance comparison between running Infinispan in all the 3 modes described. The forth plot in the chart shows the performance of running Infinispan without transactions - this gives an idea about the cost of using transactions vs. raw operations.

The benchmark was run on this Radargun configuration, using Infinispan 5.0.0.CR5 configured as shown here. As a TransactionManager JBossTS 4.15.0.FINAL was used, configured with a VolatileStore as shown here. Each node was an 4-core Intel(R) Xeon(R) CPU E5640 @ 2.67GHz, with 4GB RAM.

Each transaction spread over only one put operation. The chart shows the following:

• a non-transactional put is about 40% faster than a transactional one
• Synchronization-enlisted transactions outperform an XAResource enlisted one by about 20%
• A recoverable cache has about the same performance as a non-recoverable cache when it comes to transactions.

And that's not all! During Infinispan 5.0.0 development we've been thinking a lot about how we can improve transactional throughput, especially in scenarios in which multiple transactions are writing on the same key. As a result we've come up with some improvement suggestions summarised here: please feel free to take a look and comment!

Cheers,

Mircea