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https://issues.apache.org/jira/browse/KUDU-3011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17010231#comment-17010231
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ASF subversion and git services commented on KUDU-3011:
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Commit 4619473b9a83dce2b6a60a79802fde33c8686238 in kudu's branch
refs/heads/master from Andrew Wong
[ https://gitbox.apache.org/repos/asf?p=kudu.git;h=4619473 ]
KUDU-3011 p3: mechanism to quiesce scans
This prevents new scans from being started on a tablet server when it is
quiescing. The scans are retried elsewhere.
I added some tests to check the behavior with various non-fault-tolerant
scenarios to ensure we can rely on quiescing to move scans away from
specific tablet servers without failing read workloads. To do this, I
added some additional configuration to TestWorkload.
Change-Id: Idedca29f40b0a8576245be0f7cfad2be29db4135
Reviewed-on: http://gerrit.cloudera.org:8080/14986
Reviewed-by: Adar Dembo <[email protected]>
Tested-by: Kudu Jenkins
> Support for smooth maintenance window
> -------------------------------------
>
> Key: KUDU-3011
> URL: https://issues.apache.org/jira/browse/KUDU-3011
> Project: Kudu
> Issue Type: New Feature
> Reporter: LiFu He
> Assignee: Andrew Wong
> Priority: Major
>
> A scan corresponding to a tablet failure causes the entire SQL to fail on the
> common query engines, such as Impala. Though we have the fault-tolerant
> feature by "SetFaultTolerant()", Impala doesn't use it right now since that
> will make lower throughput. Thus, lots of SQL that are running will fail when
> we shutdown/reboot/upgrade the tserver. That can be scary.
> Maybe we can do some improvement in this area, for example, the tablets are
> not allowed to be scanned after the tserver is in maintenance mode
> (KUDU-2069). And for the LEADER_ONLY mode scanning, the leader role needs to
> be shifted from the maintenance tserver. Then we can shutdown the tserver
> smoothly after all the existing SQL are completed.
>
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