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Posted to issues-all@impala.apache.org by "Sameera Wijerathne (Jira)" <ji...@apache.org> on 2022/06/28 09:51:00 UTC
[jira] [Updated] (IMPALA-11400) Kudu scan bottleneck due to sharing a single Kudu client for multiple tablet scans
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[Sameera
Wijerathne](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=sameerawi)
**updated** an issue
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| [IMPALA](https://issues.apache.org/jira/browse/IMPALA) / [](https://issues.apache.org/jira/browse/IMPALA-11400)
[IMPALA-11400](https://issues.apache.org/jira/browse/IMPALA-11400)
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[Kudu scan bottleneck due to sharing a single Kudu client for multiple tablet
scans](https://issues.apache.org/jira/browse/IMPALA-11400)
| Change By: | [Sameera
Wijerathne](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=sameerawi)
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Attachment: | 2-1.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!
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