5.2.0.Beta6 brings a new batch of fixes around Non-Blocking State Transfer, Map/Reduce and command line interface.
But it's not only that, it also brings a bran new pice of functionality: support of concurrent updates for non-transactional caches(ISPN-2552) . Prior Infinispan 5.2.0.Beta6, there was a high chance for a deadlock to occur when two threads concurrently update the same key. This caused significant performance costs and throughput degradation, linear to the amount of contention. This functionality is enabled by default even though a compatibility mode is still available. You can read more about it here.
For a detailed list of all the issues fixed please refer the release notes.
You can download the distribution or the maven artifact. If you have any questions please check our forums, our mailing lists or ping us directly on IRC!