[jira] [Created] (SENTRY-2203) Leader Lock is not released when Sentry service shuts down

["Na Li (JIRA)" <ji...@apache.org>]

Na Li created SENTRY-2203:
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             Summary: Leader Lock is not released when Sentry service shuts down
                 Key: SENTRY-2203
                 URL: https://issues.apache.org/jira/browse/SENTRY-2203
             Project: Sentry
          Issue Type: Bug
          Components: Sentry
    Affects Versions: 2.1.0
            Reporter: Na Li
            Assignee: Na Li


In our testing for sentry HA, we found after restarting sentry service without restarting zookeeper service, it is possible that none of sentry servers is elected as leader.

What happened was
1) When a leader is elected, the sentry server host holds the leader lock. The lock is identified by the mutexPath. All sentry servers in a cluster use the same mutexPath.
2) When sentry service is shutdown, the HAContext is shutdown, so its contained CuratorFrameworkImpl was shutdown, but the leader lock was still hold by the sentry server host 
3) When the Interruption signal from shutdown caused the leader election thread to be interrupted, releasing the leader lock failed because CuratorFrameworkImpl was not in started state. 
4) When sentry server restarts, acquiring the leader lock failed because it was not released. So no active sentry servers is leader. 
5) If releasing leader lock happened before CuratorFrameworkImpl was shutdown, this issue won't happen. If restarting zookeeper after sentry service restart, this issue won't happen.

To fix this issue,

Sentry LeaderStatusMonitor can deactivate the leader to release the leader lock when it is closed, so the leader lock can be guaranteed to release before CuratorFrameworkImpl is shutdown.



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