fmt.Sprintf等等会带来大量的性能损失，在热路径上尽量避免使用。
➜ test01 git:(master) ✗ go test -v -bench=. -benchmem
testing: warning: no tests to run
BenchmarkSimpleStringAppend-4 50000000 29.9 ns/op 0 B/op 0 allocs/op
BenchmarkSimpleStringFormat-4 5000000 271 ns/op 80 B/op 5 allocs/op
PASS
ok github.com/ipfans/gobenchtest/test01 3.191s