Andrew Wong has posted comments on this change. ( http://gerrit.cloudera.org:8080/14912 )
Change subject: [tablet] Add new metrics to indicate the last read/write time ...................................................................... Patch Set 5: (4 comments) http://gerrit.cloudera.org:8080/#/c/14912/5/src/kudu/tablet/tablet.h File src/kudu/tablet/tablet.h: http://gerrit.cloudera.org:8080/#/c/14912/5/src/kudu/tablet/tablet.h@663 PS5, Line 663: // uint64_t::max is returned if this tablet hasn't been read since tablet created or tserver : // restarted. > Curious why you chose to return uint64_t::max and not 0 in these cases. My guess is the expected usage of this is to see what tablets have not been written to recently, but there's a challenge in that if you've just restarted a tserver, this metric would be 0 for all tablets. That implies that they've all been accessed very recently, which is less true than using the max value -- they've never been accessed, so the time since last access is Inf. http://gerrit.cloudera.org:8080/#/c/14912/5/src/kudu/tablet/tablet.cc File src/kudu/tablet/tablet.cc: http://gerrit.cloudera.org:8080/#/c/14912/5/src/kudu/tablet/tablet.cc@169 PS5, Line 169: since the last read operation " nit: "since the last new scan" would be more accurate. We could have created a new scanner 10 minutes ago and continue to iterate on it every 5 seconds since then, and this metric would be 10 minutes, right? If you want to measure time since access, we might have to push the metric into the iterator, but I don't have strong opinions on it, as long as it's clear what this is measuring. http://gerrit.cloudera.org:8080/#/c/14912/5/src/kudu/tablet/tablet.cc@171 PS5, Line 171: since tablet created or tserver restarted.", grammar nit: "since the tablet was created or the most recent tserver restart." Same below. http://gerrit.cloudera.org:8080/#/c/14912/5/src/kudu/tablet/tablet.cc@177 PS5, Line 177: written grammar nit: "written to" -- To view, visit http://gerrit.cloudera.org:8080/14912 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I90738ba90eaa8f78c8d721dde2eed2b723d5572d Gerrit-Change-Number: 14912 Gerrit-PatchSet: 5 Gerrit-Owner: Yingchun Lai <[email protected]> Gerrit-Reviewer: Adar Dembo <[email protected]> Gerrit-Reviewer: Alexey Serbin <[email protected]> Gerrit-Reviewer: Andrew Wong <[email protected]> Gerrit-Reviewer: Grant Henke <[email protected]> Gerrit-Reviewer: Kudu Jenkins (120) Gerrit-Reviewer: Tidy Bot (241) Gerrit-Reviewer: Yingchun Lai <[email protected]> Gerrit-Comment-Date: Wed, 18 Dec 2019 19:37:36 +0000 Gerrit-HasComments: Yes
