[jira] [Commented] (HBASE-10179) HRegionServer underreports readRequestCounts by 1 under certain conditions

["Andrew Purtell (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-10179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13849719#comment-13849719 ] 

Andrew Purtell commented on HBASE-10179:
----------------------------------------

Patch lgtm

A patch for 0.94 would be nice if you're offering. :-)

> HRegionServer underreports readRequestCounts by 1 under certain conditions
> --------------------------------------------------------------------------
>
>                 Key: HBASE-10179
>                 URL: https://issues.apache.org/jira/browse/HBASE-10179
>             Project: HBase
>          Issue Type: Bug
>          Components: metrics
>    Affects Versions: 0.94.6, 0.99.0
>            Reporter: Perry Trolard
>            Priority: Minor
>             Fix For: 0.98.0, 0.99.0
>
>         Attachments: 10179-against-trunk.diff
>
>
> In HRegionServer.scan(), if
>  (a) the number of results returned, n, is greater than zero
>  (b) but less than the size of the batch (nbRows)
>  (c) and the size in bytes is smaller than the max size (maxScannerResultSize)
> then the readRequestCount will be reported as n - 1 rather than n. (This is because the for-loop counter i is used to update the readRequestCount, and if the scan runs out of rows before reaching max rows or size, the code `break`s out of the loop and i is not incremented for the final time.)
> To reproduce, create a test table and open its details page in the web UI. Insert a single row, then note the current request count, c. Scan the table, returning 1 row; the request count will still be c, whereas it should be c + 1.
> I have a patch against TRUNK I can submit. At Splice Machine we're running 0.94, & I'd be happy to submit a patch against that as well. 



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