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https://issues.apache.org/jira/browse/HBASE-29912?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Umesh Kumar Kumawat updated HBASE-29912:
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Release Note: Behavioral change — CoDel will switch to LIFO mode earlier
under load (at the soft limit threshold rather than the hard capacity). This is
the intended/correct behavior.
Resolution: Resolved
Status: Resolved (was: Patch Available)
> Codel lifoThreshold should be applied on soft queue limit instead of hard
> limit
> -------------------------------------------------------------------------------
>
> Key: HBASE-29912
> URL: https://issues.apache.org/jira/browse/HBASE-29912
> Project: HBase
> Issue Type: Bug
> Components: rpc
> Affects Versions: 3.0.0-beta-1, 2.6.4, 2.5.13
> Reporter: Umesh Kumar Kumawat
> Assignee: Umesh Kumar Kumawat
> Priority: Major
> Labels: pull-request-available
>
> Codel switch from fifo to lifo and it does this when queue size reached an
> threshold.
> For now codel lifoThreshold is applied on hard limit. By default soft limit
> of the queue remains 100 (10 handler per queue
> (CALL_QUEUE_HANDLER_FACTOR_CONF_KEY) and we use
> DEFAULT_MAX_CALLQUEUE_LENGTH_PER_HANDLER is 10). And 250 is hard limit.
> This way we are never achiving out desired behaviour.
>
> In this Jira we will also reduce CALL_QUEUE_CODEL_DEFAULT_TARGET_DELAY to 5ms.
> I think that after HBASE-16089 codel target delay was changed to 100, that is
> not standard for CoDel ([^HBASE-16089.v3.patch]). I have changed it back.
> To visualize why we should have 5 target delay with 100 interval, I used the
> [model|https://github.com/Umeshkumar9414/hbase/blob/0056886fb540ca1cfd9035aec489a3106c47bc09/hbase-server/src/main/resources/hbase-webapps/queue-simulator/adaptive-lifo-codel-simulator.html],
> With target delay 100 and interval 100 we are more prone the queue being
> full, although CoDel will be still helpful in LIFO mode but a full queue is
> problem as it can cause OOM.
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