while reviewing SOLR-5944, I couldn't find any existing tests of doing concurrent atomic updates (ie: numeric "inc") in a cloud test. So I wrote one.
i've been hammering on this on master a bunch w/o finding any problems.
I'll commit shortly and then backport to 6x and test some more.
Commit 19044afed48aa8b5a4a53f1a722f2d193bc0da4f in lucene-solr's branch refs/heads/master from Chris Hostetter
[ https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=19044af ]
SOLR-9159: New cloud based concurrent atomic update test
Commit 1f5be04af095831c41ed2c31ba0aa3e6e3661cae in lucene-solr's branch refs/heads/branch_6x from Chris Hostetter
[ https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=1f5be04 ]
(cherry picked from commit 19044afed48aa8b5a4a53f1a722f2d193bc0da4f)