Alexey Serbin has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/19643 )

Change subject: IMPALA-12014 warning on failed KeepAlive for Kudu scanner
......................................................................


Patch Set 1:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/19643/1//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/19643/1//COMMIT_MSG@15
PS1, Line 15: This is a follow-up to f5e8047886ae7c7a9466319d86ddf9bb0c7801c3.
> nit: It's more searchable to reference the ticket number rather than commit
Done


http://gerrit.cloudera.org:8080/#/c/19643/1/be/src/exec/kudu/kudu-scanner.cc
File be/src/exec/kudu/kudu-scanner.cc:

http://gerrit.cloudera.org:8080/#/c/19643/1/be/src/exec/kudu/kudu-scanner.cc@111
PS1, Line 111:     LOG(WARNING) << BuildErrorString(
> Could this generate lots of spurious warnings? Is failing to deliver a keep
I don't expect these warnings to be spurious -- if KeepAlive has failed, then 
corresponding scanner might be GC-ed at the Kudu server.

A failed RPC means something is wrong, and that isn't supposed to happen pretty 
often.  Yes, this warning message will appear most likely if the tablet server 
hosting the replica is overloaded (e.g., with SERVICE_UNAVAILABLE error code) 
or isn't running (say, it has been stopped or exited unexpectedly).

I'm open to suggestions on how to help people to connect the dots if a scanner 
expired due to not receiving KeepAlive within its TTL.  In one particular case, 
for people with little of Kudu background it was not obvious that a scanner 
might expire just because KeepAlive didn't come through (they didn't even know 
about KeepAlive for Kudu scanners).  And none of many others bothered to look 
into Kudu logs or Kudu metrics to check for the dropped KeepScannerAlive RPCs.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: If39f968685797506491d3d5ebc481efb6e43a568
Gerrit-Change-Number: 19643
Gerrit-PatchSet: 1
Gerrit-Owner: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Michael Smith <[email protected]>
Gerrit-Comment-Date: Tue, 21 Mar 2023 21:20:43 +0000
Gerrit-HasComments: Yes

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