Announcing upgrade to Go 1.27

[dillon-zheng]

Dear developers,

We're planning to upgrade the Go version used in several core PingCAP repositories from Go 1.25.14 → Go 1.27.2.

Go 1.25 reached end of support when Go 1.27 was released (August 2026), and 1.25.14 was its final patch release. This upgrade keeps our builds on a supported toolchain and picks up the improvements introduced in Go 1.26 and Go 1.27:

• Green Tea garbage collector, enabled by default in Go 1.26, expected to reduce GC overhead by 10–40%
• Size-specialized memory allocation (Go 1.27), up to 30% faster for allocations smaller than 80 bytes
• Faster JSON handling, since encoding/json is now backed by the new encoding/json/v2 implementation
• Around 30% lower cgo call overhead, plus the usual compiler fixes and security updates

Release notes: Go 1.26 · Go 1.27

Repositories affected

• pingcap/tidb
• pingcap/ng-monitoring
• pingcap/tidb-dashboard
• pingcap/tiflow
• pingcap/ticdc
• tikv/pd

We will also align the related repositories that must be built with the exact same toolchain — such as tikv/client-go — so that downstream binaries stay compatible.

What will change

• The default Go version used in the master branch build, CI pipelines, builder images, and developer environments will be upgraded to Go 1.27.2.
• Corresponding Dockerfiles, build scripts, and release builder images will be updated to ensure compatibility.
• We will ensure that all dependencies, linting tools, and unit/integration tests pass under Go 1.27.2 before merging the upgrade.

Notes for downstream users

Go maintains its compatibility promise, so we do not expect source-level breaking changes for typical users. A few behavior changes are still worth calling out if you build or ship these components yourself:

• macOS: Go 1.27 requires macOS 13 Ventura or later, both for building and for running the resulting darwin binaries.
• TLS defaults: TLS 1.0/1.1, RSA key exchange, and 3DES are no longer enabled by default. Explicitly configured cipher suites and minimum versions still work as before.
• JSON: encoding/json is now backed by the new encoding/json/v2 implementation. Behavior is preserved, but error messages may differ and the new implementation applies stricter rules by default.
• Timers: the legacy asynctimerchan behavior has been removed, so timer channels are always unbuffered (synchronous).
• New standard library packages: encoding/json/v2, encoding/json/jsontext, uuid, and crypto/mldsa are now available.

Timeline

• Preparation and testing: ongoing
• Upgrade in master branches: planned for the coming weeks (exact dates to be confirmed)
• Backports: we also plan to backport the Go 1.27.2 upgrade to the release-8.5 branch, but the schedule is yet to be determined

How we validate before merging

• Full unit and integration regression on Go 1.27.2, compared against the current Go 1.25.14 baseline
• Performance comparison on both x86 and ARM, with no regression beyond our 5% threshold
• Long-running stability tests (48 hours and above)
• Security scanning before the upgrade is merged

Feedback and discussion

We welcome community feedback before we proceed with the upgrade.

Please share any concerns, compatibility notes, or suggestions in this discussion thread — especially if:

• You maintain downstream projects depending on these repositories.
• You have custom build environments or CI pipelines pinned to an older Go version.
• You build Go plugins against these binaries, since plugins must be compiled with the same Go toolchain as the host binary.

Thank you for your continued support and contributions!

— The PingCAP Engineering Team

[dillon-zheng]

Update (2026-10-22): darwin packages now require macOS 13+, ahead of the toolchain upgrade

Heads-up for consumers of our darwin packages: the macOS build machines have been upgraded to macOS 13.7.8 in preparation for Go 1.27, and this already changes what we publish
today:

• Every darwin artifact built by CI from now on carries LC_BUILD_VERSION.minos = 13.0 (previously 12.0).
  Verify locally: otool -l | grep -A3 LC_BUILD_VERSION
• Affected: all darwin/amd64 and darwin/arm64 packages (mainly used with tiup for local development and testing).
• Not affected: linux/amd64, linux/arm64.
• macOS 12 (Monterey) users: newly published darwin binaries will not start; please upgrade to macOS 13+ or stay on an older build.

This is the same floor that Go 1.27.2 will require anyway — it just takes effect earlier. The Go 1.27.2 upgrade itself is still in progress.