*: bump client-go to include the busy-leader probe fix (#2041) (#2044)

[ekexium]

What problem does this PR solve?

Bump github.com/tikv/client-go/v2 from v2.0.8-0.20260803075849-c3b50791b9fb to v2.0.8-0.20260806041825-494edbd79be9 on tidb-8.5, on top of the previous bump in #70303.

This brings the busy-leader probe fix (tikv/client-go#2041, cherry-picked as tikv/client-go#2044) which addresses tikv/client-go#2028: when a TiKV store's unified read pool is wedged, leader reads are rejected with ServerIsBusy(EstimatedWaitMs=0) at the pool entrance, so the request never reaches the raft layer and no NotLeader error is returned even if PD has already moved the leader away. The client then retries the stale cached leader indefinitely. After 2 consecutive such rejections within one selector, the client now probes a follower once with unchanged leader-read semantics; the follower's NotLeader reply with the real leader hint heals the shared region cache.

What is changed and how it works?

• go.mod / go.sum: client-go version bump (3 files, 5 lines changed total)
• DEPS.bzl: bazel dependency entry for the new version

Go toolchain was already bumped to 1.25.12 by #70219 / #70303; no code changes needed.

Check List

Tests:

• Unit test: go build ./... passes (only the pre-existing unrelated tools/patch-go / plugin/conn_ip_example noise)
• Integration test (CI)

Release note

None

Summary by CodeRabbit

• Chores
  • Updated the TiKV client dependency to a newer version.
  • Synchronized dependency metadata to ensure consistent builds.

[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

1. It must be LGTMed and approved by the reviewers firstly.
2. For pull requests to TiDB-x branches, it must have no failed tests.
3. AFTER it has lgtm and approved labels, please wait for the cherry-pick merging approval from triage owners.

Details

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[coderabbitai]

📝 Walkthrough

Walkthrough

The pull request updates github.com/tikv/client-go/v2 to a newer pseudo-version in go.mod and DEPS.bzl. The Bazel checksum is updated to match the new revision.

Changes

client-go dependency update

Layer / File(s)	Summary
Dependency metadata alignment go.mod, DEPS.bzl	The Go module and Bazel metadata now reference pseudo-version v2.0.8-0.20260806041825-494edbd79be9. The Bazel checksum is also updated.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

• pingcap/tidb#70301: Updates the same github.com/tikv/client-go/v2 dependency in go.mod and DEPS.bzl.
• pingcap/tidb#70303: Updates the same dependency version and checksum metadata.
• pingcap/tidb#70312: Updates the same dependency to a different revision.

Suggested reviewers: cfzjywxk, d3hunter

Poem

A rabbit checks the version line,
New client-go metadata aligns.
The checksum hops into its place,
Bazel follows at matching pace.
Two files updated, neat and bright—
Dependency paths now sit right.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the problem, implementation, testing, and release note, but it omits the required Issue Number line and side-effect and documentation sections.	Add an Issue Number: close #... or ref #... line and complete the Side effects and Documentation sections.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies the client-go dependency bump and the busy-leader probe fix.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[Copilot]

Pull request overview

Updates TiDB’s TiKV client dependency and aligns the repository’s Go toolchain to satisfy the updated client-go minimum Go requirement (release-8.5). This is primarily a dependency/toolchain maintenance change intended to pick up a client-go fix for “busy leader probe” behavior and related client improvements.

Changes:

• Bump github.com/tikv/client-go/v2 to v2.0.8-0.20260806041825-494edbd79be9 in go.mod/go.sum.
• Update Bazel dependency metadata for the new client-go version in DEPS.bzl.
• Bump Go toolchain references from 1.25.10 to 1.25.12 across build and image definitions (Go module, Bazel SDK, Dockerfiles, and build images).

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
WORKSPACE	Updates Bazel go_download_sdk version to Go 1.25.12.
Makefile.common	Updates GOTOOLCHAIN to go1.25.12 for local builds.
go.mod	Bumps Go directive to 1.25.12 and updates client-go dependency version.
go.sum	Updates checksums for the bumped client-go version.
DEPS.bzl	Updates Bazel go_repository entry (strip prefix/sha256/URLs) for new client-go version.
Dockerfile	Updates builder image to golang:1.25.12.
Dockerfile.enterprise	Updates builder image to golang:1.25.12.
build/image/base	Updates base image build ARG GOLANG_VERSION to 1.25.12.
build/image/parser_test	Updates parser test image GOLANG_VERSION to 1.25.12.

---

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[coderabbitai]

Note

GitHub couldn't provide a complete incremental comparison for this pull request, so CodeRabbit is performing a full review instead. This review may take a little longer.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (release-8.5@73f2943). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.5     #70370   +/-   ##
================================================
  Coverage               ?   55.1637%           
================================================
  Files                  ?       1852           
  Lines                  ?     666956           
  Branches               ?          0           
================================================
  Hits                   ?     367918           
  Misses                 ?     271629           
  Partials               ?      27409           

Flag	Coverage Δ
integration	38.2301% <ø> (?)
unit	65.1032% <ø> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	55.3108% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	54.8629% <0.0000%> (?)

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cfzjywxk, zyguan

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Details

Needs approval from an approver in each of these files:

• OWNERS [cfzjywxk,zyguan]

Approvers can indicate their approval by writing /approve in a comment
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-08-06 07:42:47.392346053 +0000 UTC m=+2686753.428441109: ☑️ agreed by cfzjywxk.
• 2026-08-06 07:54:41.647893321 +0000 UTC m=+2687467.683988367: ☑️ agreed by zyguan.