Github user anmolnar commented on the issue:
https://github.com/apache/zookeeper/pull/415
@phunt I asked around quickly:
HBase - own library (looks like they've started to use dropwizard somehow)
HDFS - Hadoop Metrics2 (included in hadoop-common)
Kafka - Yammer (dropwizard predecessor)
Cassandra - Yammer
I'll give dropwizard a try first.---
