[release-3.5]: use RLock in Demoted method for read-only access to expiry

[1911860538]

#19432

[k8s-ci-robot]

Hi @1911860538. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[ahrtr]

/ok-to-test

[serathius]

Please don't backport performance changes, etcd v3.6 is soon to be released. The argument that we need to backport to make it available should no longer be relevant. We should focus on releasing v3.6 and its adoption.

[1911860538]

Please don't backport performance changes, etcd v3.6 is soon to be released. The argument that we need to backport to make it available should no longer be relevant. We should focus on releasing v3.6 and its adoption.

@ahrtr @serathius Acknowledged, I am going to close this pull request.

[ahrtr]

Please don't backport performance changes, etcd v3.6 is soon to be released. The argument that we need to backport to make it available should no longer be relevant. We should focus on releasing v3.6 and its adoption.

This is not a performance fix but a correction of a misuse of sync.RWMutex, which is why backporting makes sense. That said, it’s not a critical issue, and I feel the concern here is somewhat overstated.

While 3.6 is the priority, that doesn’t mean we can’t make small, low-effort fixes along the way.

[ahrtr]

cc @fuweid @ivanvc @jmhbnz

[fuweid]

LGTM

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 1911860538, ahrtr, fuweid

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[serathius]

This is not a performance fix but a correction of a misuse of sync.RWMutex, which is why backporting makes sense. That said, it’s not a critical issue, and I feel the concern here is somewhat overstated.

Switching from Lock to RLock, doesn't fix any concurrency issue, just improves performance.

[ahrtr]

This is not a performance fix but a correction of a misuse of sync.RWMutex, which is why backporting makes sense. That said, it’s not a critical issue, and I feel the concern here is somewhat overstated.

Switching from Lock to RLock, doesn't fix any concurrency issue, just improves performance.

It's unfortunate that we're spending time debating such a trivial fix.

[fuweid]

This change is valid since RLock is read-only check. is there any concern for this change?

[ahrtr]

Let's do not waste more time on this. Let's see what other active maintainers/reviewers think. @ivanvc @jmhbnz

If majority approve, then just merge it; otherwise, just close it. Please respond on both #19443 and this PR. Thanks.