IGNITE-28105 Ensure new leader clock is not lower than last applied cmd#7731
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EgorKuts wants to merge 2 commits intoapache:mainfrom
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IGNITE-28105 Ensure new leader clock is not lower than last applied cmd#7731EgorKuts wants to merge 2 commits intoapache:mainfrom
EgorKuts wants to merge 2 commits intoapache:mainfrom
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ascherbakoff
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Mar 9, 2026
modules/raft/src/integrationTest/java/org/apache/ignite/raft/server/ItNewLeaderClockTest.java
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| this.currTerm | ||
| ); | ||
| if (request.timestamp() != null) { | ||
| clock.update(request.timestamp()); |
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Propagating HLC in each AppendEntry request creates additinal contention on HLC.
For this reason it was removed earlier.
Could we instead do it in RequestVoteRequest ?
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No. If the leader has the most advanced clock, it is possible for the new leader to have a stale clock value. This scenario is shown in the reproducer (2 out of 3 nodes have a lower HLC).
If we need to address the contention, I propose creating a separate clock per partition. This clock would be updated on each appendEntry and merged with the main clock when the node becomes a leader.
Co-authored-by: Aleksei Scherbakov <alexey.scherbakoff@gmail.com>
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It's possible that new elected leader would have a lower clock's value than the last applied command(see ItNewLeaderClockTest).
Such behavior breaks state machine invariants and causes all nodes in the replication group to fail.