Alexey Serbin has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/15794 )

Change subject: client: prefer tservers in the same location when multiple are 
local
......................................................................


Patch Set 2: Code-Review+1

(2 comments)

Thank you for fixing the flake.  I didn't get to looking at this.

http://gerrit.cloudera.org:8080/#/c/15794/2//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/15794/2//COMMIT_MSG@14
PS2, Line 14: this is an
            : actual product deficiency: if two servers are colocated, but are
            : assigned different locations, those locations should be honored 
when
            : picking tablet servers
I agree that this looks like a deficiency, but it's artificial and could be 
seen in only non-practical or misconfiguration case.

If two collocated servers are in different location, then that's sort of a 
nonsense setup.  This is because if that single node fails, servers in two 
locations become unavailable, which defies the whole idea of using location 
awareness to achieve fault tolerance.

Maybe, it's worth adding a blurb about that?


http://gerrit.cloudera.org:8080/#/c/15794/2/src/kudu/client/client-internal.cc
File src/kudu/client/client-internal.cc:

http://gerrit.cloudera.org:8080/#/c/15794/2/src/kudu/client/client-internal.cc@222
PS2, Line 222:       // 1. If there is a replica local to the client according 
to its IP and
             :       //    location, pick it. If there are multiple, pick a 
random one.
             :       // 2. Otherwise, if there is a replica in the same 
location, pick it. If
             :       //    there are multiple, pick a random one.
> I don't understand the difference between local and same location?
This might be useful to understand what location awareness means in Kudu: 
https://kudu.apache.org/docs/administration.html#rack_awareness

There is also a blogpost about this feature: 
https://kudu.apache.org/2019/04/30/location-awareness.html



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I6a0dbac073ba8a9f80a3f175157a09d06037b0df
Gerrit-Change-Number: 15794
Gerrit-PatchSet: 2
Gerrit-Owner: Andrew Wong <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Andrew Wong <[email protected]>
Gerrit-Reviewer: Bankim Bhavsar <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Comment-Date: Fri, 24 Apr 2020 07:25:52 +0000
Gerrit-HasComments: Yes

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