jiajunwang opened a new pull request #1753: URL: https://github.com/apache/helix/pull/1753
### Issues - [x] My PR addresses the following Helix issues and references them in the PR description: Resolves #1752 ### Description - [X] Here are some details about my PR, including screenshots of any UI changes: This PR fixes a potential NPE Exception that may be thrown in the DistClusterControllerStateModel state transition methods. When this error happens, a follower to leader state transition might be interrupted. The controller instance partition will be set with the ERROR state but the controller instance may have connected to the Zookeeper already. This causes inconsistency and leakage since the controller instance won't be properly cleaned up when it is dropped directly from ERROR state. ### Tests - [ ] The following tests are written for this issue: The original issue is hard to test. Especially with the fix, it is not possible to reproduce the NPE problem anymore. I suggest we mainly rely on the TestClusterStatusMonitorLifecycle to validate the correctness. It should become very stable after this change. - The following is the result of the "mvn test" command on the appropriate module: (If CI test fails due to known issue, please specify the issue and test PR locally. Then copy & paste the result of "mvn test" to here.) ### Changes that Break Backward Compatibility (Optional) - My PR contains changes that break backward compatibility or previous assumptions for certain methods or API. They include: (Consider including all behavior changes for public methods or API. Also include these changes in merge description so that other developers are aware of these changes. This allows them to make relevant code changes in feature branches accounting for the new method/API behavior.) ### Documentation (Optional) - In case of new functionality, my PR adds documentation in the following wiki page: (Link the GitHub wiki you added) ### Commits - My commits all reference appropriate Apache Helix GitHub issues in their subject lines. In addition, my commits follow the guidelines from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)": 1. Subject is separated from body by a blank line 1. Subject is limited to 50 characters (not including Jira issue reference) 1. Subject does not end with a period 1. Subject uses the imperative mood ("add", not "adding") 1. Body wraps at 72 characters 1. Body explains "what" and "why", not "how" ### Code Quality - My diff has been formatted using helix-style.xml (helix-style-intellij.xml if IntelliJ IDE is used) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
