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Merged
dominicbarnes merged 2 commits into from
Jul 18, 2025
Merged

perf(json): address performance penalty found in v0.4.0+ #149

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8487974
perf(json): revert decodeInto helper changes for object/array/string
dominicbarnes Jul 17, 2025
4e4d357
per(json): add benchmarks for decoding object and array with mixed me…
dominicbarnes Jul 17, 2025
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14 changes: 9 additions & 5 deletions json/decode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1292,15 +1292,19 @@ func (d decoder) decodeInterface(b []byte, p unsafe.Pointer) ([]byte, error) {

switch k.Class() {
case Object:
v, err = decodeInto[map[string]any](&val, v, d, decoder.decodeMapStringInterface)
m := make(map[string]interface{})
v, err = d.decodeMapStringInterface(v, unsafe.Pointer(&m))
val = m

case Array:
size := alignedSize(interfaceType)
fn := constructSliceDecodeFunc(size, sliceInterfaceType, decoder.decodeInterface)
v, err = decodeInto[[]any](&val, v, d, fn)
a := make([]interface{}, 0, 10)
v, err = d.decodeSlice(v, unsafe.Pointer(&a), unsafe.Sizeof(a[0]), sliceInterfaceType, decoder.decodeInterface)
val = a

case String:
v, err = decodeInto[string](&val, v, d, decoder.decodeString)
s := ""
v, err = d.decodeString(v, unsafe.Pointer(&s))
val = s

case Null:
v, val = nil, nil
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26 changes: 26 additions & 0 deletions json/golang_bench_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -261,6 +261,32 @@ func BenchmarkUnmarshalString(b *testing.B) {
})
}

func BenchmarkUnmarshalObjectMixed(b *testing.B) {
b.ReportAllocs()
data := []byte(`{"string":"hello world","time":"2025-07-17T18:40:04.338Z","bool":true,"integer":42,"decimal":3.14,"null":null,"object":{"hello":"world"},"array":[1,2,3]}`)
b.RunParallel(func(pb *testing.PB) {
var m map[string]any
for pb.Next() {
if err := Unmarshal(data, &m); err != nil {
b.Fatal("Unmarshal:", err)
}
}
})
}

func BenchmarkUnmarshalArrayMixed(b *testing.B) {
b.ReportAllocs()
data := []byte(`["hello world","2025-07-17T18:40:04.338Z",true,42,3.14,null,{"hello":"world"},[1,2,3]]`)
b.RunParallel(func(pb *testing.PB) {
var a []any
for pb.Next() {
if err := Unmarshal(data, &a); err != nil {
b.Fatal("Unmarshal:", err)
}
}
})
}

func BenchmarkUnmarshalFloat64(b *testing.B) {
b.ReportAllocs()
data := []byte(`3.14`)
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