release-2.1: storage: Don't transfer leases to behind replicas in StoreRebalancer #30972
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Transferring a lease to a replica that's behind can cause all requests to the range to stall, as the old leaseholder thinks it's no longer the leaseholder but the new leaseholder doesn't know it's the leaseholder yet. This avoids creating such scenarios in the StoreRebalancer. Release note (bug fix): Avoids an edge case in load-based rebalancing where we could transfer the lease for a range to a replica that isn't keeping up with the other replicas, causing brief periods where no replicas think they're leaseholder for the range and thus no requests can be processed for the range.
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petermattis
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Oct 5, 2018
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Backport 1/1 commits from #30938.
/cc @cockroachdb/release
Transferring a lease to a replica that's behind can cause all requests
to the range to stall, as the old leaseholder thinks it's no longer the
leaseholder but the new leaseholder doesn't know it's the leaseholder
yet. This avoids creating such scenarios in the StoreRebalancer.
Release note (bug fix): Avoids an edge case in load-based
rebalancing where we could transfer the lease for a range to a replica
that isn't keeping up with the other replicas, causing brief periods
where no replicas think they're leaseholder for the range and thus no
requests can be processed for the range.
Reproduction in a-robinson@933cbd5, demonstrating that transferring a lease to a behind replica causes all requests to stall.