[jira] [Updated] (SENTRY-2491) Sentry High availability unit tests run into deadlock sometimes

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

     [ https://issues.apache.org/jira/browse/SENTRY-2491?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Na Li updated SENTRY-2491:
--------------------------
    Status: Patch Available  (was: Open)

> Sentry High availability unit tests run into deadlock sometimes
> ---------------------------------------------------------------
>
>                 Key: SENTRY-2491
>                 URL: https://issues.apache.org/jira/browse/SENTRY-2491
>             Project: Sentry
>          Issue Type: Bug
>          Components: Sentry
>    Affects Versions: 2.2.0
>            Reporter: Na Li
>            Assignee: Na Li
>            Priority: Major
>         Attachments: SENTRY-2491.001.patch
>
>
> In sentry unit tests, we don't create schema before running a test. Instead, we use dataNucleus to create sentry tables when they are accessed. This creates potential deadlock when running test for Sentry HA setup. 
> For example, the following shows the event sequence that causes deadlock
> 1) thread_1 gets shared lock of SYSTABLES in order to read table SENTRY_HMS_NOTIFICATION_ID
> 2) thread_2 gets shared lock of SYSTABLES in order to read table SENTRY_HMS_NOTIFICATION_ID
> 3) thread_1 tries to get execution lock to create table SENTRY_HMS_NOTIFICATION_ID,
>    and wait for execution lock because thread_2 got shared lock already.
> 4) thread_2 tries to get execution lock to create table SENTRY_HMS_NOTIFICATION_ID,
>    and wait for execution lock because thread_1 got shared lock already.
> The solution is to let the instances of sentry service start with delay. Specifically,
> let HMS follower threads separate as far as possible, i.e., half of the interval.
>       
> This deadlock only exists in unit tests, and does not exist in production because schema is created before starting Sentry services. Therefore, there is no table creation after service starts.



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