Apache ZooKeeper release 3.4.1 is now available: this is a fix release covering 7 issues, 2 of which were considered blockers.

ZOOKEEPER-1319 is the most serious of the issues addressed, it could cause an inconsistent state in the cluster. If you are running 3.4.0 be sure to upgrade immediately:

• ZOOKEEPER-1319 Missing data after restarting+expanding a cluster

Other issues

• ZOOKEEPER-1269 Multi deserialization issues
• ZOOKEEPER-1305 zookeeper.c:prepend_string func can dereference null ptr
• ZOOKEEPER-1311 ZooKeeper test jar is broken
• ZOOKEEPER-1315 zookeeper_init always reports sessionPasswd=<hidden>
• ZOOKEEPER-1316 zookeeper_init leaks memory if chroot is just ‘/’
• ZOOKEEPER-1317 Possible segfault in zookeeper_init

Stability, Compatibility and Testing

It is important to note that 3.4.1 is not yet ready for production. It is an early release that users can start testing so that we can stabilize later 3.4.x releases.  We expect a later dot release to be production-ready soon, and will be incorporated into CDH4.

Getting Involved

The Apache ZooKeeper project is working on a number of new features. Our How To Contribute page is a great place to start if you’re interested in getting involved as a developer. You can also follow me on twitter.

Acknowledgements

A special thanks to everyone who contributed to the release (reporting issues, fixing bugs, reviewing changes, writing documentation, etc).