[CURATOR-191] Curator delivering out-of-order and duplicate events to PathChildrenCacheListener

It is very hard to reproduce, but from our procudtion logs we can see that sometimes, PathChildrenCacheListener.childEvent(..) is receiving events which are out-of-order and duplicate.

We have following line in the code...

ChildEvent child = event.getData()

log.info("CHILD_UPDATED[%s] with version[%s]", child.getPath(), event.getData().getStat().getVersion());

and observed following the logs..

2015-02-16 11:18:32,412 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[3]

2015-02-16 11:19:04,773 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[5]

2015-02-16 11:20:09,039 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[4]

2015-02-16 11:20:41,420 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[5]

2015-02-16 11:20:41,437 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[6]

2015-02-16 11:21:13,737 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[6]

2015-02-16 11:22:51,089 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[7]

2015-02-16 11:23:23,400 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[8]

2015-02-16 11:27:08,895 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[7]

2015-02-16 11:27:41,591 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[9]

2015-02-16 11:27:41,705 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[8]

2015-02-16 11:32:32,751 INFO [ServerInventoryView-0] io.druid.curator.inventory.CuratorInventoryManager - CHILD_UPDATED[2015-02-11T22:01:43.441Z3] with version[10]

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Originally reported by himanshug, imported from: Curator delivering out-of-order and duplicate events to PathChildrenCacheListener

• assignee: randgalt
  
• status: Open
  
• priority: Major
  
• resolution: Unresolved
  
• imported: 2025-01-21
  

Start at PathChildrenCacheListener.childEvent and inspect how ChildEvent data and its stat version are delivered to the listener. Use the reported path and version log sequence to investigate duplicate and out-of-order notifications; done means the listener receives events in order without duplicates, supported by a regression test or reproducible verification.

Written by the indexing model from the issue text.