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https://issues.apache.org/jira/browse/HBASE-26783?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17504496#comment-17504496
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Andrew Kyle Purtell commented on HBASE-26783:
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bq. I might be inclined to revert the branch-1 patch since this was just
opportunistically backported since branch-1 is EOL.
I will revert it. I don't have an interest in branch-1 support. Perhaps someone
else can try again.
> ScannerCallable doubly clears meta cache on retries
> ---------------------------------------------------
>
> Key: HBASE-26783
> URL: https://issues.apache.org/jira/browse/HBASE-26783
> Project: HBase
> Issue Type: Bug
> Affects Versions: 2.4.10
> Reporter: Bryan Beaudreault
> Assignee: Bryan Beaudreault
> Priority: Major
> Fix For: 2.5.0, 1.8.0, 1.7.2, 2.6.0, 2.4.11
>
>
> Way back in HBASE-15658 [~ghelmling] fixed RegionServerCallable to not clear
> meta in {{{}prepare(boolean reload){}}}. because it already would have
> cleared it in the try/catch when {{{}throwable(Throwable t, boolean
> retrying){}}}.
> I have recently been doing some load tests where I am causing HBase
> RegionServers to throw many CallDroppedExceptions because they are overloaded
> by the test. While this is an extreme example, it does sometimes crop up in
> production when a bad actor executes a job without rate limiting, etc. What I
> noticed was that the RegionServer hosting meta was most affected by the load,
> way more than any other server in the cluster. Digging into the issue I
> realized that the extra meta load was coming mostly from the scans,
> originating from {{{}ScannerCallable.prepare(boolean reload){}}}.
> I'm not sure why ScannerCallable was excluded from the original jira, maybe
> an oversight. But ScannerCallable is called in the same context of
> RetryingRpcCaller, which will handle clearing meta in the try/catch like
> other callables. We should similarly update ScannerCallable's prepare method
> not always pass useCache=true when getting region locations.
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