Go 1.7 (2016-08-15)

Go 1.7 was released in August 2016, introducing the context package, the SSA compiler backend, and significant improvements to the testing framework.

Major Changes

Toolchain

• Vendor: Vendor directory support is now enabled by default, no longer requiring GO15VENDOREXPERIMENT.

Runtime

• SSA Compiler: A new SSA (Static Single Assignment) compiler backend was enabled for the x86-64 architecture, generating more efficient code and smaller binaries.
  • Performance: Generated code typically runs 5-35% faster.
  • Size: Binary size typically reduced by 20-30%.
• Runtime: GC pause times remain low even with a large number of idle Goroutines.

Standard Library

• Context Package: golang.org/x/net/context was moved into the standard library as the context package, becoming a core component of Go concurrency patterns. It defines the Context type for carrying deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
  • Integration: Standard library packages like net, net/http, os/exec have been updated to support Context.
  • http.Request: http.Request added Context() and WithContext() methods.
• HTTP Tracing: Added the net/http/httptrace package for tracing HTTP request lifecycle events. Users can register callbacks to capture events like DNS resolution, connection establishment, TLS handshake, etc.
• Reflection: reflect.StructOf allows dynamic construction of struct types at runtime.

Testing Framework

• Subtests and Sub-benchmarks: The testing package introduced the Run method, allowing the creation of hierarchical tests and benchmarks.

  func TestFoo(t *testing.T) {
      t.Run("SubTest1", func(t *testing.T) {
          // ...
      })
      t.Run("SubTest2", func(t *testing.T) {
          // ...
      })
  }

  This makes table-driven tests more elegant and allows running specific subtests individually.

References

For more details, please refer to the official release notes: Go 1.7 Release Notes