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msmith/benchmark.md

Created November 18, 2019 16:36
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Append with preallocated capacity
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benchmark.md

Benchmarking result

$ go test -bench=.
goos: darwin
goarch: amd64
BenchmarkGrowZero-12            	 3067180	       383 ns/op
BenchmarkGrowPreallocated-12    	 7515637	       158 ns/op
PASS
ok  	_/Users/msmith/Desktop/test-alloc	4.059s
Raw
main.go
package main
import "fmt"
func main() {
GrowZero(true)
GrowPreallocated(true)
}
func GrowZero(debug bool) {
var a []int
about(debug, a)
for i := 0; i < 33; i++ {
a = append(a, i)
about(debug, a)
}
}
func GrowPreallocated(debug bool) {
a := make([]int, 0, 40)
about(debug, a)
for i := 0; i < 33; i++ {
a = append(a, i)
about(debug, a)
}
}
func about(debug bool, a []int) {
if debug {
fmt.Printf("len=%d cap=%d %v\n", len(a), cap(a), a)
}
}
Raw
main_test.go
package main
import "testing"
func BenchmarkGrowZero(b *testing.B) {
// run the Fib function b.N times
for n := 0; n < b.N; n++ {
GrowZero(false)
}
}
func BenchmarkGrowPreallocated(b *testing.B) {
// run the Fib function b.N times
for n := 0; n < b.N; n++ {
GrowPreallocated(false)
}
}
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