Hi Neha, I encountered a similar problem with zookeeper losing watches and found that it was related to this bug:
https://issues.apache.org/jira/browse/ZOOKEEPER-961 Are you using a chroot? Thanks, Jamie On Wed, Nov 2, 2011 at 1:16 PM, Neha Narkhede <[email protected]>wrote: > Hi, > > We've been seeing a problem with our zookeeper servers lately, where > all of a sudden a session loses some of the watchers registered on > some of the znodes. Let me explain our Kafka-ZK setup. We have a Kafka > cluster in one DC establishing sessions (with 6sec timeout) with a ZK > cluster (of 4 machines) in another DC and registers watchers on some > zookeeper paths. Every couple of weeks, we observe some problem with > the Kafka servers, where on investigating further, we find that the > session lost some of the key watches, but not all. > > The last time this happened, we ran the wchc command on the ZK servers > and saw the problem. Unfortunately, we lost relevant information from > the ZK logs by the time we were ready to debug it further. Since this > causes Kafka servers to stop making progress, we want to setup some > kind of alert when this happens. This will help us collect more > information to give you. Particularly, we were thinking about running > wchp periodically (maybe once a minute), grepping for the ZK paths and > counting the number of watches that should be registered for correct > operation. But I observed that the watcher info is not replicated > across all ZK servers, so we would have to query every ZK server to > inorder to get the full list. > > I'm not sure running wchp periodically on all ZK servers is the best > option for this alert. Can you think of what could be the problem here > and how we can setup this alert for now ? > > Thanks > Neha >
