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ASF GitHub Bot logged work on CURATOR-644: ------------------------------------------ Author: ASF GitHub Bot Created on: 17/Sep/22 01:39 Start Date: 17/Sep/22 01:39 Worklog Time Spent: 10m Work Description: tisonkun commented on code in PR #430: URL: https://github.com/apache/curator/pull/430#discussion_r973523533 ########## curator-recipes/src/main/java/org/apache/curator/framework/recipes/leader/LeaderLatch.java: ########## @@ -586,6 +586,9 @@ private void checkLeadership(List<String> children) throws Exception final String localOurPath = ourPath.get(); List<String> sortedChildren = LockInternals.getSortedChildren(LOCK_NAME, sorter, children); int ourIndex = (localOurPath != null) ? sortedChildren.indexOf(ZKPaths.getNodeFromPath(localOurPath)) : -1; + + log.debug("checkLeadership with ourPath: {}, children: {}", localOurPath, sortedChildren); Review Comment: Updated in e6ab28b80f19ad4c86118cd99ff7a3bee6579889. Issue Time Tracking ------------------- Worklog Id: (was: 809711) Time Spent: 5h 50m (was: 5h 40m) > 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: 5h 50m > 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. -- This message was sent by Atlassian Jira (v8.20.10#820010)