From the post:
Apache ZooKeeper release 3.3.4 is now available: this is a fix release covering 22 issues, 9 of which were considered blockers. Some of the more serious issues include:
- ZOOKEEPER-1208 Ephemeral nodes may not be removed after the client session is invalidated
- ZOOKEEPER-961 Watch recovery fails after disconnection when using chroot connection option
- ZOOKEEPER-1049 Session expire/close flooding renders heartbeats to delay significantly
- ZOOKEEPER-1156 Log truncation truncating log too much – can cause data loss
- ZOOKEEPER-1046 Creating a new sequential node incorrectly results in a ZNODEEXISTS error
- ZOOKEEPER-1097 Quota is not correctly rehydrated on snapshot reload
- ZOOKEEPER-1117 zookeeper 3.3.3 fails to build with gcc >= 4.6.1 on Debian/Ubuntu
In case you are unfamiliar with Zookeeper:
ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. All of these kinds of services are used in some form or another by distributed applications. Each time they are implemented there is a lot of work that goes into fixing the bugs and race conditions that are inevitable. Because of the difficulty of implementing these kinds of services, applications initially usually skimp on them ,which make them brittle in the presence of change and difficult to manage. Even when done correctly, different implementations of these services lead to management complexity when the applications are deployed. (from Apache Zookeeper)