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Date: Mon, 19 Dec 2016 07:17:00 +0000 (UTC)
From: "Wei Zheng (JIRA)" <jira@apache.org>
To: issues@hive.apache.org
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Subject: [jira] [Commented] (HIVE-15376) Improve heartbeater scheduling for
 transactions
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archived-at: Mon, 19 Dec 2016 07:17:01 -0000


    [ https://issues.apache.org/jira/browse/HIVE-15376?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15760406#comment-15760406 ] 

Wei Zheng commented on HIVE-15376:
----------------------------------

Yes, the call from DbTxnManagrer.acquireLocks() always uses 0 for the delay param, which is not impacted by the change.

Regarding testing heartbeat for R/O queries, I added a test case to testLockTimeout to show there's actually heartbeat being sent, otherwise the locks will be expired.

Please see patch 10.

> Improve heartbeater scheduling for transactions
> -----------------------------------------------
>
>                 Key: HIVE-15376
>                 URL: https://issues.apache.org/jira/browse/HIVE-15376
>             Project: Hive
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 2.2.0
>            Reporter: Wei Zheng
>            Assignee: Wei Zheng
>         Attachments: HIVE-15376.1.patch, HIVE-15376.2.patch, HIVE-15376.3.patch, HIVE-15376.4.patch, HIVE-15376.5.patch, HIVE-15376.6.patch, HIVE-15376.7.patch, HIVE-15376.8.patch, HIVE-15376.9.patch
>
>
> HIVE-12366 improved the heartbeater logic by bringing down the gap between the lock acquisition and first heartbeat, but that's not enough, there may still be some issue, e.g.
>  Time A: a transaction is opened
>  Time B: acquireLocks is called (blocking call), but it can take a long time to actually acquire the locks and return if the system is busy
>  Time C: as acquireLocks returns, the first heartbeat is sent
> If hive.txn.timeout < C - A, then the transaction will be timed out and aborted, thus causing failure.


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