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https://issues.apache.org/jira/browse/HBASE-1185?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12678731#action_12678731
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Jean-Daniel Cryans commented on HBASE-1185:
-------------------------------------------
Billy, I can confirm that it's scanner pre-fetching. In HRS :
{code}
public RowResult[] next(final long scannerId, int nbRows) throws IOException {
checkOpen();
requestCount.incrementAndGet();
ArrayList<RowResult> resultSets = new ArrayList<RowResult>();
try {
String scannerName = String.valueOf(scannerId);
InternalScanner s = scanners.get(scannerName);
if (s == null) {
throw new UnknownScannerException("Name: " + scannerName);
}
this.leases.renewLease(scannerName);
for(int i = 0; i < nbRows; i++) {
...
{code}
We increment for the whole batch of rows. I take the blame since it's my
modification. The fix will be easy.
> wrong request/sec in the gui reporting wrong
> --------------------------------------------
>
> Key: HBASE-1185
> URL: https://issues.apache.org/jira/browse/HBASE-1185
> Project: Hadoop HBase
> Issue Type: Bug
> Components: client, regionserver
> Affects Versions: 0.19.0
> Environment: 0.19.0
> Reporter: Billy Pearson
> Priority: Minor
> Fix For: 0.20.0
>
>
> I am seeing lower number of request in the masters gui then I have seen in
> 0.18.0 while scanning.
> I thank part of it is we moved to report per sec request not per 3 secs so
> the request should be 1/3 of the old numbers I was getting.
> hbase.client.scanner.caching is not the reason the request are under reported.
> I set hbase.client.scanner.caching = 1 and still get about 2K request a sec
> in the gui
> but when the job is done I take records / job time and get 36,324/ records
> /sec. So
> there must be some caching out side of the hbase.client.scanner.caching
> making the
> request per sec lower then it should be. I know it running faster then
> reported just thought
> it might give some new users the wrong impression that request/sec =
> read/write /sec.
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