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https://issues.apache.org/jira/browse/CURATOR-644?focusedWorklogId=803215&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-803215
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ASF GitHub Bot logged work on CURATOR-644:
------------------------------------------
Author: ASF GitHub Bot
Created on: 24/Aug/22 12:42
Start Date: 24/Aug/22 12:42
Worklog Time Spent: 10m
Work Description: XComp commented on PR #430:
URL: https://github.com/apache/curator/pull/430#issuecomment-1225671214
Fair enough. I did go through some of the commits in my IDE but just stop
(and started writing my comment) before noticing that most of the commits get
reverted again. That made me think that there's more stuff needed for
CURATOR-644. Never mind...
Issue Time Tracking
-------------------
Worklog Id: (was: 803215)
Time Spent: 1h 20m (was: 1h 10m)
> CLONE - Race conditions in LeaderLatch after reconnecting to ensemble
> ---------------------------------------------------------------------
>
> Key: CURATOR-644
> URL: https://issues.apache.org/jira/browse/CURATOR-644
> Project: Apache Curator
> Issue Type: Bug
> Affects Versions: 4.2.0
> Reporter: Ken Huang
> Assignee: Jordan Zimmerman
> Priority: Minor
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> Clone from CURATOR-504.
> We use LeaderLatch in a lot of places in our system and when ZooKeeper
> ensemble is unstable and clients are reconnecting to logs are full of
> messages like the following:
> {{{}[2017-08-31
> 19:18:34,562][ERROR][org.apache.curator.framework.recipes.leader.LeaderLatch]
> Can't find our node. Resetting. Index: -1 {{}}}}
> According to the
> [implementation|https://github.com/apache/curator/blob/4251fe328908e5fca37af034fabc190aa452c73f/curator-recipes/src/main/java/org/apache/curator/framework/recipes/leader/LeaderLatch.java#L529-L536],
> this can happen in two cases:
> * When internal state `ourPath` is null
> * When the list of latches does not have the expected one.
> I believe we hit the first condition because of races that occur after client
> reconnects to ZooKeeper.
> * Client reconnects to ZooKeeper and LeaderLatch gets the event and calls
> reset method which set the internal state (`ourPath`) to null, removes old
> latch and creates a new one. This happens in thread
> "Curator-ConnectionStateManager-0".
> * Almost simultaneously, LeaderLatch gets another even NodeDeleted
> ([here|https://github.com/apache/curator/blob/4251fe328908e5fca37af034fabc190aa452c73f/curator-recipes/src/main/java/org/apache/curator/framework/recipes/leader/LeaderLatch.java#L543-L554])
> and tries to re-read the list of latches and check leadership. This happens
> in the thread "main-EventThread".
> Therefore, sometimes there is a situation when method `checkLeadership` is
> called when `ourPath` is null.
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