This is the fifth release of BookKeeper as a subproject of Zookeeper.
This is a bugfix release for 4.2.1. There are some minor API improvements. Notably, it is now possible to check whether a ledger is closed without opening it, and it is now possible to get a list of ledgers available in the cluster.
This is the fourth release of BookKeeper as a subproject of Zookeeper. This release fixes a major performance bug in release 4.2.0. All users of BookKeeper 4.2.0 should upgrade immediately.
See BookKeeper 4.2.1 Release Notes for details.