slowjson.go

package main

import (
  "encoding/json"
	"net"
	"sync"
	"time"
)

func main() {
	l, e := net.Listen("tcp", ":3994")
	if e != nil {
		panic(e)
	}

	for {
		c, e := l.Accept()
		if e != nil {
			panic(e)
		}

		go func(c net.Conn) {
			dec := json.NewDecoder(c)
			enc := json.NewEncoder(c)
			var encl sync.Mutex
			for {
				var r map[string]interface{}
				dec.Decode(&r)
				go func() {
					time.Sleep(1 * time.Second)
					resp := map[string]interface{}{
						"jsonrpc": "2.0",
						"result":  nil,
						"id":      r["id"],
					}
					encl.Lock()
					enc.Encode(resp)
					encl.Unlock()
				}()
			}
		}(c)
	}
}