Hello Kudu Jenkins, Todd Lipcon,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/8964
to look at the new patch set (#2).
Change subject: [mvcc] Fix watermark advancement in the absence of committed
transactions
......................................................................
[mvcc] Fix watermark advancement in the absence of committed transactions
MvccSnapshot's 'none_committed_at_or_after_' (ncaoa) watermark
indicates the point after which no transactions are committed.
This is used to cull redo deltas that cannot contain any
committed transactions under a snapshot, thus reducing work when
applying deltas.
By definition, this watermark is never supposed to be lower than
the 'all_committed_before_' watermark. If this invariant is broken
delta selection might be wrong by skipping whole delta files.
Normally the ncaoa watermark is advanced when transactions are
marked as committed, in which case this is done correctly. However
there is problem when the 'all_committed_before_' watermark
is advanced and there are no committed or in flight transactions.
In this case the ncaoa watermark might be left behind, manifesting
as incorrect delta application/skipping or even crashes.
This patch includes a fix and a very directed test that makes sure
it is correct. A follow up patch includes a new test in fuzz-itest
that would trigger a crash without the fix.
Change-Id: Icf94ea289204adf2eed797c3623cdea1b11b09db
---
M src/kudu/tablet/mvcc-test.cc
M src/kudu/tablet/mvcc.cc
M src/kudu/tablet/mvcc.h
3 files changed, 50 insertions(+), 1 deletion(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/64/8964/2
--
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Icf94ea289204adf2eed797c3623cdea1b11b09db
Gerrit-Change-Number: 8964
Gerrit-PatchSet: 2
Gerrit-Owner: David Ribeiro Alves <davidral...@gmail.com>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Todd Lipcon <t...@apache.org>
