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Version: 2.9.x(Latest)

Go 1.19 (2022-08-02)

Go 1.19 was released in August 2022, mainly refining generics support, improving doc comments, and introducing important memory management features.

Major Changes​

Language​

  • Memory Model: Updated the Go memory model documentation to clarify the behavior of atomic operations, aligning with the memory models of C++20, Java, Rust, etc. Go only provides sequentially consistent atomic operations.
  • Generics: Fixed some bugs and limitations related to generics found in Go 1.18. Made a minor correction to the scope of type parameters in method declarations.

Toolchain​

  • Doc Comments: Supports richer doc comment formats, including headings, lists, and links. gofmt now reformats doc comments.

    // Package json implements encoding and decoding of JSON as defined in
    // [RFC 7159].

  • Build Constraints: Added the unix build constraint, which is satisfied when GOOS is a Unix-like system (such as linux, darwin, freebsd, etc.).

  • Go Command: Build information injected by go build now includes the -trimpath flag (if set).

Runtime​

  • GC Soft Memory Limit: Introduced the GOMEMLIMIT environment variable and runtime/debug.SetMemoryLimit function, allowing a soft memory limit to be set. This helps the GC better utilize available memory and avoid OOM, especially in container environments.
  • Dynamic Stack Sizing: Improved the initial stack sizing strategy for goroutines, allocating based on historical average usage to reduce stack copying and expansion overhead.
  • File Descriptor Limit: On Unix systems, importing the os package automatically raises the soft limit on open file descriptors to the maximum of the hard limit.

Standard Library​

  • sync/atomic: Added typed atomic types (Bool, Int32, Int64, Uint32, Uint64, Uintptr, Pointer), making them more convenient and safe to use, avoiding manual unsafe.Pointer conversions.
  • net/url: Introduced JoinPath function and URL.JoinPath method for safely joining URL paths.
  • os/exec: Command and LookPath no longer look for executables in the current directory by default (for security). Added Cmd.Environ method.
  • sort: Sorting algorithm rewritten to pattern-defeating quicksort, which is faster in many scenarios. Added Find function.
  • time: Added Duration.Abs to get the absolute value, and Time.ZoneBounds to get the time zone bounds.
  • fmt: Added Append, Appendf, Appendln functions to append formatted data to a byte slice.
  • flag: Added TextVar function, allowing flags to bind to custom types implementing the encoding.TextUnmarshaler interface.

Platform Support​

  • LoongArch: Added support for LoongArch 64-bit (linux/loong64).
  • RISC-V: The riscv64 port now supports passing function arguments and results via registers, improving performance by about 10%.

References​

For more details, please refer to the official release notes: Go 1.19 Release Notes