Dear Duo, Apologies for not understanding this. I’m not very familiar with the HBase server internals. I thought there was a link between AsyncScanSingleRegionRpcRetryingCaller#closeScanner(…) and an actual *active* close in the region server through RSRpcServices#scan(…) to RSRpcSevices#closeScanner(…) and then InternalScanner#close(). But I understand now that such a ‘kill the current scanner next RPC’ doesn’t exist.
Thanks for your guidance on this! BR, Frens Jan > On 16 May 2025, at 06:02, 张铎(Duo Zhang) <palomino...@gmail.com> wrote: > > As I explained above, there is no way to 'cancel' a running scan at > the region server side, we will remove the scanner from the lease map > while we are scanning, so sending a close scanner request to the > region server can only get an unknown scanner exception. > > You can configure 'hbase.client.scanner.timeout.period' at region > server side to control how long a scan could run, even if no entries > can be returned, the scan will stop and return a heartbeat message > back to client when reaching the time limit. > > And you can also configure a smaller scan timeout at client side, the > time limit of a scan is determine by both the client scan timeout and > 'hbase.client.scanner.timeout.period' config at region server side. > > Thanks. > > Frens Jan Rumph <frens....@web-iq.com.invalid> 于2025年5月16日周五 03:49写道： >> >> Hi Duo, >> >> Thanks for your explanation. This actually what currently is implemented; as >> in the pseudo code below. >> >> This would be beneficial of course. E.g., if a scan would be a full-table >> scan with e.g. a column name filter that doesn’t return any results, this >> would waste a lot of effort in the HBase region server. More actively >> sending a closeScanner request would prevent this. Right now, we need to >> wait for the heartbeat interval. >> >> Would such behaviour be desirable from an HBase project/community point of >> view? >> >> Best regards, >> Frens Jan >> >> >> >> >> >> >> class subscription: >> >> closed = false >> >> close(): >> close = true; >> >> onNext(results, controller): >> if(closed) >> controller.terminate(); >> else >> ... >> >> onHeartbeat(controller): >> if(closed) >> controller.terminate(); >> >> >> >> >> >> >> On 15 May 2025, at 17:24, 张铎(Duo Zhang) <palomino...@gmail.com> wrote: >> >> For asynchronous scan, we will send scan request to region server in >> background, and once there is a scan result returned from the region >> server, we can issue the next scan request. >> And in fact, we still do not have the ability to actually 'cancel' a >> scan request which is running at region server side, what we call a >> 'terminate', is to just stop issuing new scan request from client >> side. >> >> The terminate call in ScanController just tells the background task to >> stop sending new request to region server, and it is only valid when >> you have finished a scan request and get the result from region >> server. >> >> For actual implementation, since the scan request is in background, >> you can just use a flag to record that you want to terminate the scan, >> and then you are free to do anything you want. And in the next onNext >> call, you just call terminate to stop sending new scan requests. >> >> Thanks. >> >>
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