Alexey Serbin has posted comments on this change. ( http://gerrit.cloudera.org:8080/10812 )
Change subject: [rebalance-test] fix running the test on Ubuntu 18.04 ...................................................................... Patch Set 3: (1 comment) Thank you for the review. http://gerrit.cloudera.org:8080/#/c/10812/3//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/10812/3//COMMIT_MSG@17 PS3, Line 17: The motivation for this change is the fact that the test fails on : Ubuntu 18.04 without this patch. Implicitly, the reference results : relied on the order of elements in hash dictionary container used in : the implementation of the Rebalancer::KsckResultsToClusterBalanceInfo() : method. It seems the implementation of std::unordered_map in libstdc++ : shipped with Ubuntu 18.04 has changed compared with older Linux distro : versions. > FWIW, I changed all of the unordered_maps and unordered_sets in the tools/ Yep, I also did that change in the tools/ directory. In addition to that change it's necessary to change the reference results in the rebalance-test.cc so the strings for every integer key would be ordered appropriately. I didn't change the ordering of corresponding keys in the reference results because a) with this change the custom comparison operator 'normalizes' the input anyway b) the essence of this patch would not less obvious. I think it's better to use hashed dictionaries vs tree dictionaries because of faster lookup speed: O(1) instead of O(log(n)) since number of tablets might be high enough. I didn't evaluate how much gain it gives us in real world scenarios, but I suspect there is some. As for the iterating over those maps, the order of elements there is not crucial except for the reference results comparison. We talked about that with Will and decided to keep hashed maps. If we find the regular tree maps are better, we can easily switch at any point. -- To view, visit http://gerrit.cloudera.org:8080/10812 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: Ie4dc5d22bab86f6ab61f18f05e45a063bbf38eba Gerrit-Change-Number: 10812 Gerrit-PatchSet: 3 Gerrit-Owner: Alexey Serbin <[email protected]> Gerrit-Reviewer: Adar Dembo <[email protected]> Gerrit-Reviewer: Alexey Serbin <[email protected]> Gerrit-Reviewer: Tidy Bot Gerrit-Reviewer: Will Berkeley <[email protected]> Gerrit-Comment-Date: Wed, 27 Jun 2018 17:16:28 +0000 Gerrit-HasComments: Yes
