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ASF GitHub Bot logged work on CURATOR-498: ------------------------------------------ Author: ASF GitHub Bot Created on: 21/Feb/19 18:47 Start Date: 21/Feb/19 18:47 Worklog Time Spent: 10m Work Description: Randgalt commented on issue #303: [CURATOR-498] Protected Mode creation can mistake closing session's node causing problems for many recipes such as LeaderLatch URL: https://github.com/apache/curator/pull/303#issuecomment-466118760 > does Curator 2.x suffer this issue and if so, will we make a backport bugfix? No, I don't think it does. Curator 2.0 does not do "fake" session expiration. That was added in 3.x. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org Issue Time Tracking ------------------- Worklog Id: (was: 202154) Time Spent: 50m (was: 40m) > Protected Mode creation can mistake closing session's node causing problems > for many recipes such as LeaderLatch > ---------------------------------------------------------------------------------------------------------------- > > Key: CURATOR-498 > URL: https://issues.apache.org/jira/browse/CURATOR-498 > Project: Apache Curator > Issue Type: Bug > Components: Framework > Affects Versions: 4.0.1, 4.1.0 > Environment: ZooKeeper 3.4.13, Curator 4.1.0 (selecting explicitly > 3.4.13), Linux > Reporter: Shay Shimony > Assignee: Jordan Zimmerman > Priority: Blocker > Fix For: 4.2.0 > > Attachments: CURATOR-498.png, HaWatcher.log, LeaderLatch0.java, > ha.tar.gz, logs.tar.gz, reproduction.tar.gz, reproduction2.tar.gz > > Time Spent: 50m > Remaining Estimate: 0h > > The Curator app I am working on uses the LeaderLatch to select a leader out > of 6 clients. > While testing my app, I noticed that when I make ZK lose its quorum for a > while and then restore it, then after Curator in my app restores it's > connection to ZK - sometimes not all the 6 clients are found in the latch > path (using zkCli.sh). That is, I have 5 instead of 6. > After investigating a little, I have a suspicion that LeaderLatch deleted the > leader in method setNode. > To investigate it I copied the LeaderLatch code and added some log messages, > and from them it seems like very old create() background callback was > surprisingly scheduled and corrupted the current leader with its stale path > name. Meaning, this old one called setNode with its stale name, and set > itself instead of the leader and deleted the leader. This leaves client > running, thinking it is the leader, while another leader is selected. > If my analysis is correct then it seems like we need to make this obsolete > create callback cancelled (I think its session was suspended on 22:38:54 and > then lost on 22:39:04 - so on SUSPENDED cancel ongoing callbacks). > Please see attached log file and modified LeaderLatch0. > > In the log, note that on 22:39:26 it shows that 0000000485 is replaced by > 0000000480 and then probably deleted. > Note also that at 22:38:52, 34 seconds before, we can see that it was in the > reset() method ("RESET OUR PATH") and possibly triggered the creation of > 0000000480 then. -- This message was sent by Atlassian JIRA (v7.6.3#76005)