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Version: 2.9.x(Latest)

Go 1.12 (2019-02-25)

Go 1.12 was released in February 2019, focusing on runtime performance improvements, module support, and preliminary support for TLS 1.3.

Major Changes​

Toolchain​

  • Go Modules Improvements:
    • go directive: The go.mod file now supports the go directive (e.g., go 1.12) to specify the language version used by the module's code.
    • Concurrent Downloads: The go command can now download and extract modules concurrently.
    • Module Awareness: When GO111MODULE=on, the go command supports module-aware operations even outside of a module directory.
  • go vet Rewrite: The go vet command has been rewritten based on the new golang.org/x/tools/go/analysis framework, making it more modular and powerful.
  • Build Cache: The build cache is now mandatory to speed up the build process.
  • Godoc: godoc no longer provides a command-line interface and runs only as a web server. For command-line help, use go doc.

Runtime​

  • Memory Release: The runtime now more aggressively returns unused memory to the operating system. On Linux, it defaults to using MADV_FREE, which may cause RSS to appear higher, but the memory is actually reclaimable by the system. To restore the old behavior, set GODEBUG=madvdontneed=1.
  • GC Scanning: Significantly improved scanning performance when most of the heap is live, reducing allocation latency after GC.
  • Timer Optimization: Optimized performance of timers and deadlines, especially in high-concurrency scenarios.

Standard Library​

  • TLS 1.3 Support (Optional): Go 1.12 introduces optional support for TLS 1.3. It is disabled by default and can be enabled by setting the environment variable GODEBUG=tls13=1. It will be enabled by default in Go 1.13.
  • strings / bytes: Added ReplaceAll function to replace all occurrences of a substring, which is more concise than Replace(s, old, new, -1).
  • os: Added UserHomeDir function to get the current user's home directory.
  • fmt: Map printing order is now fixed (sorted by key) to facilitate testing.
  • runtime/debug: Added BuildInfo type and ReadBuildInfo function to read build information (module version, etc.) from binaries.

Platform Support​

  • Windows/ARM: Support for running Go on Windows 10 IoT Core (e.g., Raspberry Pi 3).
  • AIX: Support for AIX 7.2 and later (aix/ppc64).
  • macOS: Go 1.12 is the last version to support macOS 10.10 Yosemite.

References​

For more details, please refer to the official release notes: Go 1.12 Release Notes