Go 1.24 rc2

1.go

import (
	"testing"
)

func BenchmarkOld(b *testing.B) {
	for n := 0; n < b.N; n++ {
		try()
	}
}

func BenchmarkOld2(b *testing.B) {
	for range b.N {
		try()
	}
}

func BenchmarkNew(b *testing.B) {
	for b.Loop() {
		try()
	}
}

// Run
$go1.24rc2 test -bench=.   

goos: darwin
goarch: arm64
pkg: demo
cpu: Apple M2 Max
BenchmarkOld-12     	1000000000	         0.2963 ns/op
BenchmarkOld2-12    	1000000000	         0.2917 ns/op
BenchmarkNew-12     	593273757	         2.006 ns/op
PASS
ok  	demo	2.435s

2.go

package main

import (
	"fmt"
	"runtime"
	"time"
)

type Resource struct {
	Id   int
	Name string
}

func release(time time.Time) {
	fmt.Println("Release resource at", time)
}

// Run
$go1.24rc2 run clean.go

Release resource at 2025-02-05 22:40:32.22332 +0700 +07 m=+0.000141001
func makeResource() *Resource {
	r := &Resource{}
	// Register the resource for cleanup
	runtime.AddCleanup(r, release, time.Now())
	return r
}

func main() {
	// Create a resource
	makeResource()

	// Force GC to run
	runtime.GC()

	// Wait for the cleanup to run
	time.Sleep(100 * time.Millisecond)
}

3.go

package main

import (
	"testing"
	"testing/synctest"
	"time"
)

func TestMyConcurrentCode(t *testing.T) {
	// Run the test with a timeout of 5 seconds
	synctest.Run(func() {
		go func() {
			time.Sleep(5 * time.Second)
		}()

		// Wait for the goroutine to finish
		synctest.Wait()
	})
}

// Run
$GOEXPERIMENT=synctest  go1.24rc2 test ./... -v

=== RUN   TestMyConcurrentCode
--- PASS: TestMyConcurrentCode (0.00s)
PASS
ok  	demo	0.192s

4.go

package main

import (
	"io"
	"log/slog"
)

func main() {
	// Discard log output with slog

	// Old way
	log1 := slog.New(
		slog.NewTextHandler(io.Discard, nil),
	)
	log1.Info("This will not be printed")

	// New way
	log2 := slog.New(slog.DiscardHandler)
	log2.Info("This will not be printed")
}