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Max peer_horizon_lsn before adopting it.

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Before this patch, persistent peer_horizon_lsn was always sent to walproposer,
making it initially calculate it equal to max of persistent values and in turn
pulling back the in memory value. Send instead in memory value and take max when
safekeeper sets it.

closes https://github.com/neondatabase/neon/issues/3752
This commit is contained in:
Arseny Sher
2023-03-06 14:20:58 +04:00
committed by Arseny Sher
parent 7b9057ad01
commit ca85646df4
1 changed files with 10 additions and 3 deletions
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13
safekeeper/src/safekeeper.rs
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@@ -191,7 +191,8 @@ pub struct SafeKeeperState {
/// Minimal LSN which may be needed for recovery of some safekeeper (end_lsn
/// of last record streamed to everyone). Persisting it helps skipping
/// recovery in walproposer, generally we compute it from peers. In
/// walproposer proto called 'truncate_lsn'.
/// walproposer proto called 'truncate_lsn'. Updates are currently drived
/// only by walproposer.
pub peer_horizon_lsn: Lsn,
/// LSN of the oldest known checkpoint made by pageserver and successfully
/// pushed to s3. We don't remove WAL beyond it. Persisted only for
@@ -682,7 +683,7 @@ where
term: self.state.acceptor_state.term,
vote_given: false as u64,
flush_lsn: self.flush_lsn(),
truncate_lsn: self.state.peer_horizon_lsn,
truncate_lsn: self.inmem.peer_horizon_lsn,
term_history: self.get_term_history(),
timeline_start_lsn: self.state.timeline_start_lsn,
};
@@ -878,7 +879,13 @@ where
if msg.h.commit_lsn != Lsn(0) {
self.update_commit_lsn(msg.h.commit_lsn)?;
}
self.inmem.peer_horizon_lsn = msg.h.truncate_lsn;
// Value calculated by walproposer can always lag:
// - safekeepers can forget inmem value and send to proposer lower
// persisted one on restart;
// - if we make safekeepers always send persistent value,
// any compute restart would pull it down.
// Thus, take max before adopting.
self.inmem.peer_horizon_lsn = max(self.inmem.peer_horizon_lsn, msg.h.truncate_lsn);
// Update truncate and commit LSN in control file.
// To avoid negative impact on performance of extra fsync, do it only