Hello Mike Percy, Kudu Jenkins,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/11142
to look at the new patch set (#7).
Change subject: KUDU-2463 pt 1: adjust MVCC when replaying no-ops
......................................................................
KUDU-2463 pt 1: adjust MVCC when replaying no-ops
Previously, during tablet bootstrap, a tablet replica would only update
its MVCC safetime based on write and alter schema messages, as the
timestamps in these messages are guaranteed to be serialized with
respect to one another, by virtue of being assigned in a single thread
(the prepare thread) on the leader replica.
From this, we conclude that timestamps for write and alter schema
operations are monotonically increasing in unison with opid. The same
cannot necessarily be said for timestamps of no-ops and change configs.
This is a conservative conclusion about assigned timestamps, and this
patch hinges on the fact that our Raft implementation ensures the
following sequence of events:
1. replica A becomes leader of Term N
2. leader A assigns a timestamp t1 to its no-op
3. leader A replicates the no-op to replicas B and C, asserting its
leadership for Term N
4. leader A prepares a write and assigns it a timestamp t2 > t1
5. leader A replicates the write to replicas B and C, checking that it
is leader for the Term N
Given the above series of operations, within the same term, the no-op
used to assert leadership is always assigned a timestamp that must be
lower than any other ops in that term. As such, the timestamps assigned
to no-ops can and should be used to bump safetime. This patch does so at
bootstrap time with committed no-ops found in the WAL.
This alone isn't enough to prevent KUDU-2463, but it reduces the window
during which incorrect results can be returned.
Change-Id: I26deff32da8c990cb8a2ba220bb81858ddd6d73f
---
M src/kudu/consensus/consensus.proto
M src/kudu/integration-tests/CMakeLists.txt
M src/kudu/integration-tests/raft_consensus-itest.cc
A src/kudu/integration-tests/timestamp_advancement-itest.cc
M src/kudu/tablet/tablet_bootstrap-test.cc
M src/kudu/tablet/tablet_bootstrap.cc
6 files changed, 276 insertions(+), 9 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/42/11142/7
--
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I26deff32da8c990cb8a2ba220bb81858ddd6d73f
Gerrit-Change-Number: 11142
Gerrit-PatchSet: 7
Gerrit-Owner: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Mike Percy <mpe...@apache.org>
