gopls/v0.12.0

This release contains a major rewrite of the way gopls computes and stores package information, with the goal of reducing memory usage and allowing gopls to scale to larger repositories. This change can also significantly reduce startup time when workspaces are reopened, as gopls now uses a file-based cache to persist data across sessions. With these optimizations, gopls is finally able to fully analyze dependencies using the golang.org/x/tools/go/analysis framework, resulting in improved accuracy for analysis diagnostics.

You can install this release with go install:

go install golang.org/x/tools/gopls@v0.12.0

Support changes

As gopls matures, we're trying to simplify its configuration so that gopls Just Works in more scenarios, and so that we have fewer configuration combinations to test. This means that we will be gradually deprecating settings that affect the core behavior of gopls.

Removed experimental configuration options

As announced in the v0.10.0 release notes, this release removes support for the experimentalWorkspaceModule and experimentalWatchedFileDelay settings. The experimentalPackageCacheKey setting is also removed, as it is irrelevant in the new design.

The experimentalWorkspaceModule setting in particular may still be in use by some users. This setting has been superseded by built-in support for multi-module workspaces in the go command, via Go workspaces. To get the equivalent behavior in gopls@v0.12.0, please create a go.work file in your workspace using all desired modules. To use all modules in your workspace, run:

Dropped support for Go 1.13-1.15, deprecated support for Go 1.16-1.17

As announced in the v0.10.0 release notes, this release drops support for Go 1.13-1.15, and in fact does not build with these Go versions.

Additionally, gopls@v0.12.x will be the final sequence of versions supporting Go 1.16-1.17, and therefore displays a deprecation notice when used with these Go versions.

Supported operating systems

Given that our users are almost entirely on Linux, Windows, or Darwin, we are discussing narrowing our support to focus on those operating systems, in golang/go#59981.

Performance improvements

The banner feature of this release is an internal redesign that significantly improves the way gopls scales in larger codebases. Performance, particularly memory usage, has long been a pain point for our users.

Reduced memory usage

Previous releases of gopls held typed syntax trees for all packages, in memory, all the time. With this release, these large data structures are ephemeral: as soon as they are constructed, an index of information derived from them is saved persistently to a file-based cache, and the data structures are recycled. The index for each package includes the locations of declaring and referring identifiers; the set of exported declarations and their types; the method sets of each interface; and any diagnostics and facts (see below) produced during analysis. The index holds all the information needed to serve global-scope LSP queries such as “references”, “implementations”, and so on.

Moving package information to a file-based cache greatly reduces the amount of RAM gopls uses, by almost an order of magnitude in larger projects. The table below shows the reductions in steady-state memory usage for three open-source Go repositories.