Zero-Allocation JSON Parsing: Benchmarking Sonic, EasyJSON, and Go-JSON

In high-load REST APIs, JSON serialization and deserialization accounts for 40% to 60% of total CPU request processing time. Go's standard encoding/json library is robust and safe, but relies heavily on runtime reflection. This analysis evaluates state-of-the-art zero-allocation alternatives for high-throughput pipelines.

1. Comprehensive JSON Engine Comparison

Library	Core Mechanism	Unmarshal Speed	Heap Allocs
`encoding/json`	Runtime Reflection	1.0x (Baseline)	High
`bytedance/sonic`	JIT Assembly (AVX2)	4.5x faster	Near-zero
`mailru/easyjson`	Static Code Generation	3.8x faster	Zero-alloc
`goccy/go-json`	Fast AST & SIMD	3.2x faster	Low

2. Zero-Copy String to Byte Slice in Go 1.20+

Standard casting []byte(str) allocates a brand new slice on the heap. Modern Go provides official zero-copy utilities through unsafe:

zero_copy.go

package zero

import "unsafe"

// Zero-copy string to byte slice without heap allocation
func StringToBytes(s string) []byte {
	return unsafe.Slice(unsafe.StringData(s), len(s))
}

// Zero-copy byte slice to string without heap allocation
func BytesToString(b []byte) string {
	return unsafe.String(unsafe.SliceData(b), len(b))
}