[3.5] backport for fix retry requests when receiving ErrGPRCNotSupportedForLearner

[sheyt0]

Backport of PR #12985

[k8s-ci-robot]

Hi @sheyt0. Thanks for your PR.

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[ivanvc]

Hi @sheyt0, thanks for the pull request. Please ensure your commit is signed so the Developer Certificate of Origin (DCO) check passes, i.e:

git rebase HEAD~1 --signoff
git push --force

/ok-to-test

[fuweid]

LGTM

[jmhbnz]

LGTM - Thanks @sheyt0

[serathius]

/cc @ahrtr

[ahrtr]

I do not see any big problem on this PR. But for safety, I suggest that we do not change the error code in stable release.

But I agree that we should backport the change in isSafeRetry, we do need to instruct the client to retry when it receives an ErrGPRCNotSupportedForLearner error and len(endpoints) > 1.

[sheyt0]

Who decides what form a fix should take?
I can fix the backport by only including the change for replays for learner. But I expect at least some comments on this matter.

[ahrtr]

@sheyt0 please follow my comment above #17641 (comment) to update this PR.

• We do need to update isSafeRetry as this PR already did
• Regarding the error code changes, as I mentioned above, I did not see any big problem. But it changes the protocol between client and server, so I suggest not to change them in stable releases.

[ahrtr]

@sheyt0 can you also please backport the fix to 3.4?

And also update the changelog for both 3.5 and 3.4 in a separate PR?