AlphaCanisMajoris opened a new pull request, #2152: URL: https://github.com/apache/zookeeper/pull/2152
This fix aims to fix a bunch of issues in follower's syncWithLeader(). It is built upon #2111 and inspired by #1848. #2111 can avoid [ZOOKEEPER-4643](https://issues.apache.org/jira/browse/ZOOKEEPER-4643), but it cannot fix other issues like [ZOOKEEPER-4394](https://issues.apache.org/jira/browse/ZOOKEEPER-4394): the NullPointerException problem when the follower receives COMMIT after replying NEWLEADER ack in syncWithLeader(). In #1848, when receiving NEWLEADER, the follower only persists and processes the packets according to "packetsCommitted". It guarantees no loss of committed txns because the follower syncs the leader's committed history before replying NEWLEADER ack. Besides, it avoids [ZOOKEEPER-4394](https://issues.apache.org/jira/browse/ZOOKEEPER-4394) by keeping the outstanding proposals in "packetsNotCommitted" to avoid NullPointerException when receiving COMMIT packet(s) right after replying NEWLEADER ack. Integrated by #2111 and #1848, this fix avoids a group of issues in SYNCHRONIZATION, including [ZOOKEEPER-4643](https://issues.apache.org/jira/browse/ZOOKEEPER-4643), [ZOOKEEPER-4646](https://issues.apache.org/jira/browse/ZOOKEEPER-4646), [ZOOKEEPER-4685](https://issues.apache.org/jira/browse/ZOOKEEPER-4685), [ZOOKEEPER-4394](https://issues.apache.org/jira/browse/ZOOKEEPER-4394) and the problem of flaky tests [ZOOKEEPER-3023](https://issues.apache.org/jira/browse/ZOOKEEPER-3023). More importantly, we have leveraged the TLA+ specifications of ZooKeeper and verified the correctness of this fix. -- 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. To unsubscribe, e-mail: notifications-unsubscr...@zookeeper.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
