Added detection of the node with longest log during leader election process #17915
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bharathv
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src/v/raft/vote_stm.cc
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| return with_gate( | ||
| _vote_bg, | ||
| [this] { | ||
| return _sem.wait(_ptr->_jit.base_duration(), 1); |
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we can only wait for
(_requests_dispatched_ts + _ptr->_jit.base_duration() - clock_type::now()) ?
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i think it depends, the vote_request timeout is larger than the election timeout, indeed i can adjust wait timeout here to be dependent from the dispatch timestamp
Signed-off-by: Michał Maślanka <michal@redpanda.com>
Signed-off-by: Michał Maślanka <michal@redpanda.com>
Signed-off-by: Michał Maślanka <michal@redpanda.com>
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Signed-off-by: Michał Maślanka <michal@redpanda.com>
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ci failure: #17847 |
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Making Raft leader election unsuccessful if one of the votes has log which is more up to data than the current candidate. This solution will allow us to minimise the data loss risk when using relaxed consistency writes. With the optimisation included in this PR a candidate will wait up to election timeout for the replies from all of the nodes and will fail the leader election if any of the voters log is more up to date. The solution included in this PR favour the nodes with longest log to become a leader without compromising availability as it is still enough for the majority to vote for the candidate for it to become a leader.
Another way of seeing this solution is that the candidate will use information about voter logs if they are available instead of ignoring the one with longest log and moving on with the majority based decision.
The detection mechanism can be controller in runtime with
raft_enable_longest_log_detectioncluster configuration flag.Backports Required
Release Notes
Improvements