Go Wiki: Go-Release-Cycle

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Short link: https://go.dev/s/release.

Overview

Go is released every six months. Each release cycle is broken down into a development phase lasting about 4 months, followed by a 3-month period of testing and polishing called the release freeze. If everything goes well, work on the next release begins before the previous release has shipped, resulting in an overlap of about a month.

After the initial release of a version, it is supported with minor releases that fix severe bugs and security issues.

Timeline

The current release cycle is aligned to start in mid-January and mid-July of each year. The target milestones for a release cycle are as described below. We try to hit the targets as closely as possible, while still delivering a quality release.

To give the team time to prepare, and to address unexpected problems, we prefer to do release work early or mid-week. That means that exact dates will vary year to year, so milestones are specified as weeks in a particular month. Week 1 is the week starting on the first Monday of the month. All dates are subject to change based on the year’s holiday timings.

January / July week 1: Planning for release begins.

Planning of major work for upcoming release cycle is announced on golang-dev.

Example: Go 1.20

January / July week 3: Release work begins.

Once the prior release has entered its final stabilization period, the tree opens for general development. All kinds of development are welcome during this period. It’s preferable for large or particularly risky changes to land well before the end of the development window, so that there’s time to fix any problems that arise with them.

May / November week 4: Release freeze begins.

This milestone begins the second part of the release cycle, the release freeze. The release freeze applies to the entire main repository as well as to the code in subrepositories that is needed to build the binaries included in the release, particularly vet and all its dependencies in the tools subrepository.

During the freeze, only bug fixes, test-only changes, and doc updates are accepted. On occasion new work may be done during the freeze, but only in exceptional circumstances and typically only if the work was proposed and approved before the cutoff. Such changes must be low risk. See freeze exceptions below.

This part of the release cycle is focused on improving the quality of the release, by testing it and fixing bugs that are found. However, every fix must be evaluated to balance the benefit of a possible fix against the cost of now having not as well tested code (the fix) in the release. Early in the release cycle, the balance tends toward accepting a fix. Late in the release cycle, the balance tends toward rejecting a fix, unless a case can be made that the fix is both low risk and high reward.

Examples of low risk changes appropriate late in the cycle include changes to documentation and fixes to new features being introduced in the current release (since there is no chance of introducing a regression compared to an earlier release).

Shortly after the freeze begins, nearly all known bugs should have been fixed or explicitly postponed (either to the next release or indefinitely). The remainder should usually be tracked as release blockers and worked on urgently.

June / December week 2: Release candidate 1 issued.

A release candidate is meant to be as close as possible to the actual release bits. Issuing a release candidate is an indication that the Go team has high confidence that the tree is free of critical bugs. In particular, because Google continuously tracks the development version of Go, by the time a release candidate is issued, a close approximation of it will have been running in production at Google for at least a week or two.

Once a release candidate is issued, only documentation changes and changes to address critical bugs should be made. In general the bar for bug fixes at this point is even slightly higher than the bar for bug fixes in a minor release. We may prefer to issue a release with a known but very rare crash than to issue a release with a new but not production-tested fix.

If critical bugs are reported and fixed, additional release candidates may be issued, but typically not more than one every two weeks.

Again, a release candidate is meant to be bug-free, as much as possible. Organizations are encouraged to deploy it in production settings after appropriate organization-specific testing.

The calm period between a release candidate and the final release is a good time for additional testing or for discussing the next release (see the planning milestone above).

July / January week 3: Work on the next release begins

While the current release is being stabilized, the tree reopens for work on the next. During this period, fixes intended for the current release need to be cherry-picked onto the release branch. Unlike cherry-picks for minor releases, these changes don’t need a backport issue and don’t need to be approved by the release team. As long as they’re permitted by the freeze policy, they can be reviewed and submitted like any other CL.

August / February week 2: Release issued.

Finally, the release itself!

A release should not contain significant changes since the last release candidate: it is important that all code in the release has been well tested. Issuing a release is an indication that release testing has confirmed the release candidate’s high confidence that the tree is free of critical bugs.

Even if a release goes smoothly and there’s spare time, we prefer to stay on schedule. Extra testing can only improve the stability of a release, and it also gives developers working on the Go release more time to think about and plan the next release before code changes start pouring in again.

By the time of the final release, Google will have been using this version of Go for nearly two months. While Google’s successful use does not guarantee the absence of problems, our experience has been that it certainly helps improve the quality of the release. We strongly encourage other organizations to test release candidates as aggressively as they are able and to report problems that they find.

Once a release is stabilized, work on the next release, including code reviews and submission of new code, can begin, and the cycle repeats. Note that if a release is delayed, work on the next release may be delayed as well.

Release Maintenance

A minor release is issued to address one or more critical problems for which there is no workaround (typically related to stability or security). The only code changes included in the release are the fixes for the specific critical problems. Important documentation-only changes and safe test updates (such as disabling tests), may also be included as well, but nothing more. Minor releases preserve backwards compatibility as much as possible, and don’t introduce new APIs.

Minor releases to address problems (including security issues) for Go 1.x stop once Go 1.x+2 is released. For more about security updates, see the security policy.

See also the MinorReleases wiki page.

Freeze Exceptions

Fix CLs that are permitted by the freeze policy do not need a freeze exception.

Any exceptions to the freeze must be communicated to and explicitly approved by the Go Release Team before the freeze. If you’d like to request an exception, please file an issue in the issue tracker with “[freeze exception]” as a suffix and include “CC @golang/release” (example). We will address any requests on a case-by-case basis with a strong preference for not permitting changes after the freeze.

Historical note

A version of this schedule, with a shorter development window, was originally adopted for the Go 1.7 release in 2016. After years of difficult releases, testing and process improvements in 2022 and 2023 led to a timely 1.19 release. For 1.20, the development window was expanded with a late freeze and early thaw. These changes were formalized for the 1.21 release. We anticipate continuing to ship on time.

This content is part of the Go Wiki.