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https://issues.apache.org/jira/browse/HBASE-18000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16005665#comment-16005665
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Karan Mehta commented on HBASE-18000:
-------------------------------------
[~Apache9]
This is a corner case. I feel that the bug is not fully resolved.
We have set the {{scannerId}} on the {{ScanResponse}} builder
{code}
if (request.hasScannerId()) {
rsh = getRegionScanner(request);
isSmallScan = false;
// The downstream projects such as AsyncHBase in OpenTSDB need this
value. See HBASE-18000
// for more details.
builder.setScannerId(request.getScannerId());
} else {
{code}
and {{rsh = getRegionScanner(request);}} look like this
{code}
if (request.hasCloseScanner() && request.getCloseScanner()) {
throw SCANNER_ALREADY_CLOSED;
} else {
{code}
which implies that for a {{CloseScannerRequest}} an exception is thrown by this
line. Thus, {{builder.setScannerId(request.getScannerId())}} is never executed.
We thus send an empty {{ScanResponse}} for handling it as follows.
{code}
if (e == SCANNER_ALREADY_CLOSED) {
// Now we will close scanner automatically if there are no more results
for this region but
// the old client will still send a close request to us. Just ignore it
and return.
return builder.build();
}
{code}
Thus there is no {{scannerId}} added in the {{builder}}.
A simple possible fix is to do this. Please suggest.
{code}
if (request.hasScannerId()) {
- rsh = getRegionScanner(request);
- isSmallScan = false;
// The downstream projects such as AsyncHBase in OpenTSDB need this
value. See HBASE-18000
// for more details.
builder.setScannerId(request.getScannerId());
+ rsh = getRegionScanner(request);
+ isSmallScan = false;
} else {
{code}
> Make sure we always return the scanner id with ScanResponse
> -----------------------------------------------------------
>
> Key: HBASE-18000
> URL: https://issues.apache.org/jira/browse/HBASE-18000
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 2.0.0, 1.4.0, 1.3.1
> Reporter: Lars Hofhansl
> Assignee: Duo Zhang
> Fix For: 2.0.0, 1.4.0, 1.3.2
>
> Attachments: HBASE-18000.patch
>
>
> Some external tooling (like OpenTSDB) relies on the scanner id to tie
> asynchronous responses back to their requests.
> (see comments on HBASE-17489)
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