As of go 1.22, there's no need to use the unsafe package for string to bytes conversion #124656
Closed as not planned
Description
What would you like to be added?
As of go 1.22, for string to bytes conversion, we can replace the usage of unsafe.Slice(unsafe.StringData(s), len(s)) with type casting []bytes(str), without the worry of losing performance.
As of go 1.22, string to bytes conversion []bytes(str) is faster than using the unsafe package. Both methods have 0 memory allocation now.
I saw at least two places in the codebase still using the unsafe way:
Here's my benchmark results, comparing two ways of conversion:
╰─○ go test -v -run=none -bench=. -benchmem=true
goos: darwin
goarch: amd64
pkg: example.com/m/v2
cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
BenchmarkStringToBytesUnsafe
BenchmarkStringToBytesUnsafe-12 1000000000 0.5636 ns/op 0 B/op 0 allocs/op
BenchmarkStringToBytesCasting
BenchmarkStringToBytesCasting-12 1000000000 0.2548 ns/op 0 B/op 0 allocs/op
PASS
ok example.com/m/v2 1.448sMy test code:
package main
import (
"testing"
"unsafe"
)
const (
str = "some random string"
)
func toBytes(s string) []byte {
// unsafe.StringData is unspecified for the empty string, so we provide a strict interpretation
if len(s) == 0 {
return nil
}
// Copied from go 1.20.1 os.File.WriteString
// https://github.com/golang/go/blob/202a1a57064127c3f19d96df57b9f9586145e21c/src/os/file.go#L246
return unsafe.Slice(unsafe.StringData(s), len(s))
}
func toBytesRaw(s string) []byte {
return []byte(s)
}
func BenchmarkStringToBytesUnsafe(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = toBytes(str)
}
}
func BenchmarkStringToBytesCasting(b *testing.B) {
for i := 0; i < b.N; i++ {
_ = toBytesRaw(str)
}
}
Why is this needed?
- Kubernetes as of now is built with go 1.22, in go 1.22 type casting is faster than unsafe, regarding only string to bytes conversion
- We can make string to bytes conversion faster with type casting
- We don't need to be 'unsafe' anymore