OCPBUGS-100390: UPSTREAM: 21443: Revert "Reuse events between sync loops"

[redhat-chai-bot]

Cherry-pick: etcd memory regression fix for 4.21

Cherry-pick of upstream etcd-io/etcd#21443 — Revert "Reuse events between sync loops"

Problem

etcd 3.6 introduced a memory regression that scales with cluster size (OCPBUGS-76329). The rangeEventsWithReuse optimization held event objects across sync loops, causing unbounded memory growth:

Cluster Size	etcd 3.5 Max RSS	etcd 3.6 Max RSS	Max Change
24 nodes	468 MiB	541 MiB	+15.6%
120 nodes	893 MiB	1.24 GiB	+42.2%
250 nodes	1.13 GiB	2.96 GiB	+162%

Fix

This cherry-picks the upstream revert which:

• Removes the rangeEventsWithReuse function
• Removes the shared evs variable from syncWatchersLoop
• Restores the original rangeEvents and kvsToEvents signatures with contains filtering

Why cherry-pick instead of full rebase

OCP 4.21 etcd is on 3.6.5. A full rebase to 3.6.9+ is complicated by Go version constraints (see openshift/etcd#377 which is held). This targeted cherry-pick addresses the critical memory regression without introducing other changes.

Build and test verification

• go build ./... ✅
• go test ./server/storage/mvcc/... ✅ (11.7s)

References

• Upstream issue: Increased memory usage with 3.6 event reuse etcd-io/etcd#21355
• Upstream fix: [release-3.6] Revert "Reuse events between sync loops" etcd-io/etcd#21443
• Jira: https://redhat.atlassian.net/browse/OCPBUGS-76329
• 4.22 rebase (includes this fix): OCPBUGS-82497: Rebase v3.6.13 for openshift-4.22 #393

---

@sdodson requested in Slack thread

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository: openshift/coderabbit/.coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 60313b36-dcad-4278-9091-502d80444ce1

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[openshift-ci]

@redhat-chai-bot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/upstream-integration	0ff063b	link	false	/test upstream-integration
ci/prow/upstream-e2e	0ff063b	link	false	/test upstream-e2e

Full PR test history. Your PR dashboard.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

Approval requirements bypassed by manually added approval.

This pull-request has been approved by: redhat-chai-bot

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[sdodson]

/jira cherry-pick OCPBUGS-76329

[openshift-ci-robot]

@sdodson: Jira Issue OCPBUGS-76329 has been cloned as Jira Issue OCPBUGS-100390. Will retitle bug to link to clone.
/retitle OCPBUGS-100390: UPSTREAM: 21443: Revert "Reuse events between sync loops"

Details

In response to this:

/jira cherry-pick OCPBUGS-76329

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[openshift-ci-robot]

@redhat-chai-bot: This pull request references Jira Issue OCPBUGS-100390, which is invalid:

• expected dependent Jira Issue OCPBUGS-76329 to be in one of the following states: VERIFIED, RELEASE PENDING, CLOSED (ERRATA), CLOSED (CURRENT RELEASE), CLOSED (DONE), CLOSED (DONE-ERRATA), but it is ON_QA instead

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

The bug has been updated to refer to the pull request using the external bug tracker.

Details

In response to this:

Cherry-pick: etcd memory regression fix for 4.21

Cherry-pick of upstream etcd-io/etcd#21443 — Revert "Reuse events between sync loops"

Problem

etcd 3.6 introduced a memory regression that scales with cluster size (OCPBUGS-76329). The rangeEventsWithReuse optimization held event objects across sync loops, causing unbounded memory growth:

Cluster Size	etcd 3.5 Max RSS	etcd 3.6 Max RSS	Max Change
24 nodes	468 MiB	541 MiB	+15.6%
120 nodes	893 MiB	1.24 GiB	+42.2%
250 nodes	1.13 GiB	2.96 GiB	+162%

Fix

This cherry-picks the upstream revert which:

• Removes the rangeEventsWithReuse function
• Removes the shared evs variable from syncWatchersLoop
• Restores the original rangeEvents and kvsToEvents signatures with contains filtering

Why cherry-pick instead of full rebase

OCP 4.21 etcd is on 3.6.5. A full rebase to 3.6.9+ is complicated by Go version constraints (see openshift/etcd#377 which is held). This targeted cherry-pick addresses the critical memory regression without introducing other changes.

Build and test verification

• go build ./... ✅
• go test ./server/storage/mvcc/... ✅ (11.7s)

References

• Upstream issue: Increased memory usage with 3.6 event reuse etcd-io/etcd#21355
• Upstream fix: [release-3.6] Revert "Reuse events between sync loops" etcd-io/etcd#21443
• Jira: https://redhat.atlassian.net/browse/OCPBUGS-76329
• 4.22 rebase (includes this fix): OCPBUGS-82497: Rebase v3.6.13 for openshift-4.22 #393

---

@sdodson requested in Slack thread

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.