Go 1.14 (2020-02-25)

Go 1.14 was released in February 2020, marking that Go Modules are ready for production use, and bringing significant runtime performance improvements.

Major Changes

Language

• Overlapping Interfaces: Allows embedded interfaces to define overlapping methods. This solves common problems in complex interface embedding structures (such as diamond inheritance).

  type ReadWriteCloser interface {
      io.ReadCloser
      io.WriteCloser
  }
  // Even though both ReadCloser and WriteCloser contain the Close() method, this is now legal.

Toolchain

• Modules Production Ready: The implementation of Go Modules is mature enough that the official recommendation is for all users to use it for dependency management in production environments.
  • Vendor Behavior: If the main module contains a vendor directory, the go command now defaults to using -mod=vendor.
  • GOINSECURE: Added the GOINSECURE environment variable to fetch modules via HTTP without certificate validation (mainly for internal private repositories).

Runtime

• Defer Performance: The overhead of defer statements has been drastically reduced and is now almost negligible. Developers can confidently use defer for resource cleanup in performance-sensitive code.
• Goroutine Asynchronous Preemption: Implemented signal-based asynchronous preemption scheduling. This means tight loops (e.g., for loops without any function calls) will no longer block the GC or scheduler, greatly reducing STW (Stop-The-World) latency and avoiding potential deadlocks.
• Timer Efficiency: More efficient internal timer implementation, reducing lock contention and context switching.

Standard Library

• hash/maphash: Added hash/maphash package, providing high-performance hash functions for hash tables (Note: generated hash values are not consistent across processes and should not be persisted).
• testing:
  • T.Cleanup / B.Cleanup: Register cleanup functions to be executed after the test or benchmark finishes (similar to defer, but more flexible).
• math:
  • math.FMA: Added Fused Multiply-Add (x*y+z) operation, utilizing hardware instructions to improve precision and performance.
• sync:
  • Mutex: Improved Mutex performance under high contention by directly yielding the CPU to waiting Goroutines.
• TLS: Removed support for SSLv3. TLS 1.3 can no longer be disabled via GODEBUG.
• HTTP/2: net/http's test server (httptest) now supports HTTP/2.

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References

For more details, please refer to the official release notes: Go 1.14 Release Notes