Go 1.3 (2014-06-18)

Go 1.3 was released in June 2014, mainly improving stack management, garbage collector, and toolchain performance, and adding support for several new operating systems.

Major Changes

Toolchain

• Godoc: The godoc tool added static analysis capabilities (via the -analysis flag), which can display call graphs, type relationships, etc.
• Linker: The linker was refactored, moving some instruction selection work to the compiler stage, significantly speeding up compilation for large projects.
• New Platform Support: Added support for DragonFly BSD, Plan 9, Solaris, and NaCl (Native Client).

Runtime

• Contiguous Stacks: Go 1.3 changed the goroutine stack implementation from a segmented model to a contiguous model. When stack space is insufficient, the runtime allocates a larger contiguous memory block and copies the old stack over. This eliminates the "hot split" performance issue caused by repeated expansion and contraction at segment boundaries in segmented stacks.
• Precise GC: The garbage collector can now precisely identify pointers on the stack. This means non-pointer data (like integers) will not be mistaken for pointers, avoiding memory leaks.
• Map Iteration: Restored random iteration order for small Maps (<= 8 elements) to prevent programs from relying on specific iteration orders (the Go language specification explicitly states that Map iteration order is undefined).
• Defer Performance: Reduced the overhead of defer, reducing memory allocation by about 2KB per defer call.

Standard Library

• sync.Pool: This is an important new type used to store and reuse temporary objects. It can reduce pressure on the garbage collector, especially in high-concurrency scenarios.

  var bufPool = sync.Pool{
      New: func() interface{} {
          return new(bytes.Buffer)
      },
  }

• TCP Keep-Alive: HTTP clients (DefaultTransport) and servers now enable TCP Keep-Alive by default.

References

For more details, please refer to the official release notes: Go 1.3 Release Notes