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https://issues.apache.org/jira/browse/HBASE-26783?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17499864#comment-17499864
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Bryan Beaudreault commented on HBASE-26783:
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This is only an issue in 1.x and 2.x. In fact, the async implementation in
master seems to not refresh meta for scanner failures at all (though it does
for other call types). That may be a separate bug.
> 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
>
> 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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