[jira] [Updated] (HBASE-28396) Quota throttling can cause a leak of scanners

["Nick Dimiduk (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-28396?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Nick Dimiduk updated HBASE-28396:
---------------------------------
    Fix Version/s: 2.7.0
                   3.0.0-beta-2
                   2.6.1

> Quota throttling can cause a leak of scanners
> ---------------------------------------------
>
>                 Key: HBASE-28396
>                 URL: https://issues.apache.org/jira/browse/HBASE-28396
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Bryan Beaudreault
>            Assignee: Hernan Gelaf-Romer
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 2.7.0, 3.0.0-beta-2, 2.6.1
>
>
> In RSRpcServices.scan, we check the quota after having created a new RegionScannerHolder. If the quota is exceeded, an exception will be thrown. In this case, we can't send the scannerName back to the client because it's just an exception. So the client will be forced to retry the openScanner call, but the RegionScannerHolder is not closed. Eventually the scanners will be cleaned up by the lease expiration, but this could cause many scanners to leak during periods of high throttling.
> We could close the newly opened scanner before throwing the throttle exception, but I think it's better to not open the scanner at all until we've grabbed some quota.



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