Go 1.26 Recap: Green Tea GC Is On

Go recap series — one short post per release. Released February 2026.

TL;DR

• Green Tea GC is the default: 10–40% less GC overhead.
• new(expr) — make a pointer from a value in one step.
• errors.AsType[T](err) — errors.As without the extra variable.
• go fix ./... upgrades old code to modern Go.
• cgo calls ~30% cheaper, io.ReadAll ~2× faster.

1. Green Tea GC

What changed: the garbage collector now scans small objects one memory page (span) at a time, instead of jumping from object to object across the heap.

The Go team expects 10–40% less GC overhead in real programs, and about 10% more on newer CPUs (Intel Ice Lake, AMD Zen 4 and later).

Why it matters: less CPU spent on GC, by just upgrading.

2. new(expr)

type User struct {
    Age *int `json:"age,omitzero"`
}

// before: age := yearsSince(born); u := User{Age: &age}
u := User{Age: new(yearsSince(born))}

Why it matters: optional pointer fields without a temporary variable.

3. errors.AsType

if pathErr, ok := errors.AsType[*fs.PathError](err); ok {
    log.Println("failed path:", pathErr.Path)
}

Why it matters: shorter, type-safe, and faster than errors.As.

4. go fix modernizes your code

$ go fix ./...

What it does: rewrites old patterns to modern Go features and APIs.

Why it matters: run it after every upgrade — free cleanup.

5. Worth knowing

• Generic types can reference themselves in constraints: type Adder[A Adder[A]] interface { Add(A) A }.
• log/slog.NewMultiHandler sends logs to several handlers.
• crypto/hpke (new) and post-quantum TLS key exchanges enabled by default.
• Experimental: goroutine leak profile and simd/archsimd.

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Source: Go 1.26 release notes