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Posted to issues-all@impala.apache.org by "Daniel Becker (Jira)" <ji...@apache.org> on 2022/11/23 10:57:00 UTC
[jira] [Updated] (IMPALA-11400) Kudu scan bottleneck due to sharing a single Kudu client for multiple tablet scans
[ https://issues.apache.org/jira/browse/IMPALA-11400?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Daniel Becker updated IMPALA-11400:
-----------------------------------
Fix Version/s: Impala 4.3.0
(was: Impala 4.2.0)
> Kudu scan bottleneck due to sharing a single Kudu client for multiple tablet scans
> ----------------------------------------------------------------------------------
>
> Key: IMPALA-11400
> URL: https://issues.apache.org/jira/browse/IMPALA-11400
> Project: IMPALA
> Issue Type: Bug
> Components: Backend
> Affects Versions: Impala 4.1.0
> Reporter: Sameera Wijerathne
> Priority: Major
> Labels: performance
> Fix For: Impala 4.3.0
>
> Attachments: 0.JPG, 1.JPG, 2-1.jpeg, 2.JPG, 2.jpeg, 3.JPG, 4.JPG, 5.JPG, Impala_1.png, Impala_2.png, Kudu_1.png, Kudu_2.png, WhatsApp Image 2022-06-07 at 10.39.27 PM.jpeg
>
>
> This issue was observed when impala queries large datasets resides in Kudu. Even single ImpalaD is scanning multiple kudu tablets, it shows a slowness to retrive data eventhough ImpalaD makes parrellel scans. Reason for this is ImpalaD only uses a single Kudu client for multiple scans but KuduScanner::NextBatch runs on a single thread. So it's rpc reactor thread utilizes upto a single core and bottlenecks all parrelel scans.
> This behaviour makes Impala clusters that scans kudu cannot be vertically scales to the maximum performance/cores of a node.
> Please refer the screenshots from Kudu slack channel for more information.
>
> !2-1.jpeg|width=717,height=961!
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