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https://issues.apache.org/jira/browse/HBASE-26726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17484977#comment-17484977
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Andrew Kyle Purtell edited comment on HBASE-26726 at 1/31/22, 10:42 PM:
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Hey [~bbeaudreault] as I explained this isn't about avoiding fixing a bug. That
is being handled on the other mentioned issue and the upgrade issue only
produces warnings.
In case it wasn't clear, I think warmup is an architectural problem because it
invalidates the assumption regionservers have that they have exclusive
ownership of store files. It is technically a double assignment case. This
can't really be fixed IMHO. So I want to shut it off in my deployments.
At the same time I recognize that maybe others will have performance concerns,
so they can leave it on. "I've never had a problem with this" etc. I don't want
to have those arguments.
Default remains on for backwards compatibility.
was (Author: apurtell):
Hey [~bbeaudreault] as I explained this isn't about avoiding fixing a bug. That
is being handled on the other mentioned issue and the upgrade issue only
produces warnings.
In case it wasn't clear, I think warmup is an architectural problem because it
invalidates the assumption regionservers have that they have exclusive
ownership of store files. It is technically a double assignment case. This
can't really be fixed IMHO. So I want to shut it off in my deployments.
At the same time I recognize that maybe others will have performance concerns,
so they can leave it on.
Default remains on for backwards compatibility.
> Allow disable of region warmup before graceful move
> ---------------------------------------------------
>
> Key: HBASE-26726
> URL: https://issues.apache.org/jira/browse/HBASE-26726
> Project: HBase
> Issue Type: Improvement
> Components: master, Region Assignment
> Reporter: Andrew Kyle Purtell
> Assignee: Andrew Kyle Purtell
> Priority: Minor
> Fix For: 2.5.0, 1.7.2, 2.6.0, 3.0.0-alpha-3
>
>
> We have encountered two issues with region warmup before the assignment
> manager gracefully moves a region from one regionserver to another.
> The first instance is HBASE-26722. Part of the failure chain is temporary
> double assignment like conditions where both the source and destination
> regionservers think they have exclusive rights to storefile management (as
> they should) but warmup opens a region before it is closed and then both
> regionservers take compaction related actions. While this can be remediated
> with more care to this case, it is unclear if warmup affords significant
> advantage. The motivation of the original commit in 2015 introducing this
> feature was avoidance of blockcache misses once region ownership transfer was
> advertised to clients. Depending on use case and additional default-false
> schema options (like preload) this could be valuable. Or not.
> The second instance is in place upgrade from HBase 1 to HBase 2. In a
> scenario where regionservers have been replaced by HBase 2 versions, but the
> master is still HBase 1, the region warmup RPC request fails. This is not
> particularly harmful but indicates it will not be useful during the
> transition period.
> We think it would be good to allow for warmup before move to be optionally
> disabled by a site configuration setting. In particular there have been many
> unrelated changes committed since 2015 and expectations of invariants in the
> contribution of the warmup-on-move feature have been invalidated. HBASE-26722
> may be the only case, or it might not. This is a fairly trivial change.
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