I don't believe ZooKeeper watches maintain a memory of events that occurred while you were disconnected. It's been a very long time since I looked at this code but my memory is that if you are disconnected you will miss events. Not just with persistent watches but with any watches.
-Jordan > On Jul 25, 2025, at 2:22 AM, Li Wang <li4w...@gmail.com> wrote: > > Hello, > > I wonder if anyone knows whether persistent recursive watch ensures that > the client receives notifications for any changes that occurred while > disconnected? > > The feature was introduced in > https://issues.apache.org/jira/browse/ZOOKEEPER-1416. > > Following the code, it looks like it only re-registers the watches but > doesn't check if any changes have occurred and need to be notified upon > reconnecting. > > I wonder if anyone has any knowledge and insight on this. Any > response would be appreciated. > > > Code snippet in DataTree.setWatches() > ============================= > > for (String path : persistentWatches) { > this.childWatches.addWatch(path, watcher, > WatcherMode.PERSISTENT); > this.dataWatches.addWatch(path, watcher, > WatcherMode.PERSISTENT); > } > for (String path : persistentRecursiveWatches) { > this.dataWatches.addWatch(path, watcher, > WatcherMode.PERSISTENT_RECURSIVE); > } > > https://github.com/apache/zookeeper/blob/master/zookeeper-server/src/main/java/org/apache/zookeeper/server/DataTree.java#L1492-L1529 > > > Thanks > > Li
