Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

release-23.1.0: Revert "kvserver: allow expired leases to quiesce" #101912

Merged

Conversation

erikgrinaker
Copy link
Contributor

Backport 1/1 commits from #101899.

/cc @cockroachdb/release


This reverts commit 76afb00.

This change was flawed, because it assumed an expired lease would have to be reacquired which would wake up the range, but that's not necessarily true. In cases where the Raft leader is not colocated with the leaseholder, the Raft leader may have a stale liveness record, or the leaseholder may temporarily fail to heartbeat liveness without anyone bumping its epoch. If this happens, it's possible for an expired lease to revert to a valid lease from the leader's point of view, but at that point it's too late: the range is already quiesced.

This can prevent e.g. lease transfers, because we don't allow leaseholders to transfer their lease if they're not the Raft leader (they need to make sure the target is not behind on the Raft log). We won't attempt to colocate the Raft leader with the leaseholder for a quiesced range, since we don't tick it.

Touches #101885.
Touches #97289.

Epic: none
Release note: None

This reverts commit 76afb00.

This change was flawed, because it assumed an expired lease would have
to be reacquired which would wake up the range, but that's not
necessarily true. In cases where the Raft leader is not colocated with
the leaseholder, the Raft leader may have a stale liveness record, or
the leaseholder may temporarily fail to heartbeat liveness without
anyone bumping its epoch. If this happens, it's possible for an expired
lease to revert to a valid lease from the leader's point of view, but at
that point it's too late: the range is already quiesced.

This can prevent e.g. lease transfers, because we don't allow
leaseholders to transfer their lease if they're not the Raft leader
(they need to make sure the target is not behind on the Raft log). We
won't attempt to colocate the Raft leader with the leaseholder for a
quiesced range, since we don't tick it.

Epic: none
Release note: None
@erikgrinaker erikgrinaker self-assigned this Apr 20, 2023
@erikgrinaker erikgrinaker requested a review from a team April 20, 2023 14:04
@erikgrinaker erikgrinaker requested a review from a team as a code owner April 20, 2023 14:04
@blathers-crl
Copy link

blathers-crl bot commented Apr 20, 2023

Thanks for opening a backport.

Please check the backport criteria before merging:

  • Patches should only be created for serious issues or test-only changes.
  • Patches should not break backwards-compatibility.
  • Patches should change as little code as possible.
  • Patches should not change on-disk formats or node communication protocols.
  • Patches should not add new functionality.
  • Patches must not add, edit, or otherwise modify cluster versions; or add version gates.
If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.
  • There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
  • The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
  • New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters.
  • The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

  • What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
  • Will this work in a cluster of mixed patch versions? Did we test that?
  • If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

@cockroach-teamcity
Copy link
Member

This change is Reviewable

Copy link
Member

@tbg tbg left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Clean, right?

@erikgrinaker
Copy link
Contributor Author

Yeah, minor test conflict.

@erikgrinaker erikgrinaker merged commit a5e2c5b into cockroachdb:release-23.1.0 Apr 20, 2023
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

4 participants