Alexey Serbin has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/16655 )

Change subject: [tserver] validator for --scanner_max_wait_ms
......................................................................


Patch Set 2:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/16655/2/src/kudu/tserver/tablet_service.cc
File src/kudu/tserver/tablet_service.cc:

http://gerrit.cloudera.org:8080/#/c/16655/2/src/kudu/tserver/tablet_service.cc@204
PS2, Line 204: at least up to $2
> nit: "to at least $2", otherwise this may read as though the user should in
Done


http://gerrit.cloudera.org:8080/#/c/16655/2/src/kudu/tserver/tablet_service.cc@210
PS2, Line 210:   return true;
> Is this to say that it's not actually that critical an issue? Will snapshot
Some background behind this: I was looking at one issue from the fields and I 
initially thought that the problem was related to a difference in local time 
between tablet servers.   I had a theory about distribution of tablet replicas 
when the client was writing and reading back from a follower replica with a 
lagging local clock.

However, after deeper investigation I realized that was not likely the case.  I 
found that the issue is most likely related to a fact that the follower replica 
which was a source for a timed out snapshot scan had accumulated many 
operations because and was slow to apply those.

With these findings, I guess trying to force this  relationship between 
--scanner_max_wait_ms and --raft_heartbeat_interval_ms doesn't make much sense 
unless we think it's common to have few seconds difference in local clock among 
different tablet servers.  I guess the latter is very unlikely, and it should 
rather be considered as an anomaly.

With that, I don't think we want to introduce this validator, actually.  So, I 
moved the rest of the changes into a separate changelist and posted it for 
review: https://gerrit.cloudera.org/#/c/16669/

Meanwhile, I'm abandoning this changelist.



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I1dec4173a9ae50a4de34b909283c5a2ee4ef9166
Gerrit-Change-Number: 16655
Gerrit-PatchSet: 2
Gerrit-Owner: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Andrew Wong <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Comment-Date: Wed, 28 Oct 2020 03:52:13 +0000
Gerrit-HasComments: Yes

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