sizeof

calculate memory usage base on reflect

install

go get github.com/3vilive/sizeof

usage

integer:

var (
i8int8i16int16i32int32i64int64
)
fmt.Printf("size of i8: %d bytes\n", sizeof.SizeOf(i8))
fmt.Printf("size of i16: %d bytes\n", sizeof.SizeOf(i16))
fmt.Printf("size of i32: %d bytes\n", sizeof.SizeOf(i32))
fmt.Printf("size of i64: %d bytes\n", sizeof.SizeOf(i64))
// output:// size of i8: 1 bytes// size of i16: 2 bytes// size of i32: 4 bytes// size of i64: 8 bytes

string:

varstr1="hello"fmt.Printf("size of `%s`: %d bytes\n", str1, sizeof.SizeOf(str1))
fmt.Printf("16 (size of string underlying struct) + %d (size of content)\n", len(str1) *8)
// output:// size of `str1`: 56 bytes// 16 (size of string underlying struct) + 40 (size of content)

pointer:

varstrPtr1=&str1fmt.Printf("size of `strPtr1`: %d bytes\n", sizeof.SizeOf(strPtr1))
fmt.Printf("8 (size of pointer) + 56 (size of string)\n")
// output:// size of `strPtr1`: 64 bytes// 8 (size of pointer) + 56 (size of string)

array:

vararr= [3]int64{1, 2, 3}
fmt.Printf("size of `arr`: %d bytes\n", sizeof.SizeOf(arr))
// output:// size of `arr`: 24 bytes

slice:

var (
slice1 []int64=nilslice2= []int64{}
slice3= []int64{1, 2, 3}
)
fmt.Printf("size of `slice1`: %d bytes\n", sizeof.SizeOf(slice1))
fmt.Printf("size of `slice2`: %d bytes\n", sizeof.SizeOf(slice2))
fmt.Printf("size of `slice3`: %d bytes\n", sizeof.SizeOf(slice3))
// output:// size of `slice1`: 0 bytes// size of `slice2`: 24 bytes// size of `slice3`: 48 bytes

map:

var (
map1map[int64]int64=nilmap2=map[int64]int64{}
map3=map[int64]int64{1: 1, 2: 2}
)
fmt.Printf("size of `map1`: %d bytes\n", sizeof.SizeOf(map1))
fmt.Printf("size of `map2`: %d bytes\n", sizeof.SizeOf(map2))
fmt.Printf("size of `map3`: %d bytes\n", sizeof.SizeOf(map3))
// output:// size of `map1`: 0 bytes// size of `map2`: 8 bytes// size of `map3`: 40 bytes

struct:

typeDemo1struct {
aint8
}
typeDemo2struct {
aint8bint64// align: 7
}
typeDemo3struct {
a*Demo1b*Demo2
}
typeDemo4struct {
Demo3usernamestringposts []string
}
fmt.Printf("size of `Demo1`: %d bytes\n", sizeof.SizeOf(Demo1{}))
fmt.Printf("size of `Demo2`: %d bytes\n", sizeof.SizeOf(Demo2{}))
fmt.Printf("size of `Demo3`: %d bytes\n", sizeof.SizeOf(Demo3{}))
fmt.Printf("size of `Demo3 with values`: %d bytes\n", sizeof.SizeOf(Demo3{
a: &Demo1{},
b: &Demo2{},
}))
fmt.Printf("size of `Demo4 with values`: %d bytes\n", sizeof.SizeOf(Demo4{
Demo3: Demo3{
a: &Demo1{},
b: &Demo2{},
},
username: "3vilive",
posts: []string{"sizeof is awesome"},
}))
// output:// size of `Demo1`: 1 bytes// size of `Demo2`: 16 bytes// size of `Demo3`: 16 bytes// size of `Demo3 with values`: 33 bytes// size of `Demo4 with values`: 281 bytes