Bankim Bhavsar has posted comments on this change. ( http://gerrit.cloudera.org:8080/14745 )
Change subject: Import Impala's blocked based BloomFilter ...................................................................... Patch Set 4: > Patch Set 4: > > > Patch Set 4: Verified-1 > > > > Build Failed > > > > http://jenkins.kudu.apache.org/job/kudu-gerrit/19688/ : FAILURE > > > /home/jenkins-slave/workspace/kudu-master/1/src/kudu/util/block_bloom_filter-test.cc:179 > > Expected: (found) <= (find_limit * expected_fpp * 8), actual: 51 vs 48.0793 > > Too many false positives with -log2(fpp) = 11 > > Looks like change to use SeedRandom() that uses current time instead of > earlier fixed seed srand(0) is exposing some issue in the false-positive rate > observed. > > I took a peek why the expected range of fpp is 1x >= expected fpp <= 8x but > couldn't find a good reason looking at Impala git history. > > Investigating further... With dist-test looping for 1000 times or so with random seed, FindInvalid test would fail ~10% for lower false positive rate (1.0/ (1 << 11)) to (1.0 / (1 << 15)). I also tried different random number generation mechanisms but results were same. Bumped up the range for assertion from 8x and 16x and haven't seen any failures with multiple dist test runs. -- To view, visit http://gerrit.cloudera.org:8080/14745 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I89c54a051c5093cf5fb81481a47a0a6677d7d906 Gerrit-Change-Number: 14745 Gerrit-PatchSet: 4 Gerrit-Owner: Bankim Bhavsar <[email protected]> Gerrit-Reviewer: Adar Dembo <[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-Reviewer: Thomas Tauber-Marshall <[email protected]> Gerrit-Reviewer: Tidy Bot (241) Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Reviewer: Todd Lipcon <[email protected]> Gerrit-Comment-Date: Wed, 27 Nov 2019 16:27:55 +0000 Gerrit-HasComments: No
