Dear hakkers,

We are excited to announce a new patch release of Akka 2.6. Noteworthy additions and improvements in this release:

• Addition of Durable State persistence, see below.
• Exclude exiting members in Read/Write MajorityPlus, which is used by Sharding #30327
• Gracefully terminating shard region unnecessarily delays further rebalancing #30401
• Coalesce writes in TCP Streams #30334
• Possibility to configure log levels for backoff restarts for Streams and Actors #30445

2.6.16 includes 44 closed issues. The complete list can be found on the 2.6.16 milestone on github.

Durable State

Durable State is a new persistence model that complements Event Sourced persistence. It’s useful when only the latest state is of interest. The full state is stored and it overwrites previously stored state. In contrast, Event Sourcing stores all events (changes) leading up to the current state and recovers the state by replaying the events.

The API of DurableStateBehavior should be familiar to you that have already used EventSourcedBehavior and it is typically used together with Cluster Sharding. See examples in the documentation.

There is support for queries and Projections to retrive a Stream of the state of all (tagged) entities.

Database specific implementations have so far been added to the JDBC 5.0.2 and Spanner 1.0.0-RC10 plugins of Akka Persistence and Akka Projections 1.2.2.

The API will be marked “may change” for a few patch releases before we declare it final. Take it for a spin and let us know what you think!

Rolling upgrades

This release includes a new Akka Cluster Sharding internal message that is used whenever a shard region is terminated (see #30402). If you run a rolling upgrade, you might see deserialization warnings for message RegionStopped in the logs of the oldest node (the one holding the shard coordinator). It’s safe to ignore those warnings during the upgrade.

Credits

For this release we had the help of 23 committers – thank you all very much!

commits  added  removed
     48    815      772 Arnout Engelen
     15   4125      192 Patrik Nordwall
     10    599      207 Johan Andrén
      9   2561      116 Debasish Ghosh
      8     60       40 Andrea Peruffo
      7    320       28 Ignasi Marimon-Clos
      6     20       13 Yury Gribkov
      4    211       61 Renato Cavalcanti
      4     19       45 Captain1653
      3    346      115 Raymond Roestenburg
      2     20       19 Johannes Rudolph
      1    109        2 economist
      1      9       66 Peter Vlugter
      1     34       35 Lukas Rytz
      1     55        0 eyal farago
      1     14       14 Daryl Odnert
      1      3        9 Levi Ramsey
      1      5        5 marcoderama
      1      2        2 Ryan Burke
      1      3        1 Michael Rose
      1      1        2 Josep Prat
      1      2        0 franciscolopezsancho
      1      1        1 Kris Kalavantavanich

Lightbend employs the Akka core team. If you’re looking to take your Akka systems to the next level, let’s set up a time to discuss our enterprise-grade expert support, self-paced education courses, and technology enhancements that help you manage, monitor and secure your Akka systems - from development to production.

Happy hakking!

– The Akka Team