0 packet result in coroutine leak

count_co.lua

local skynet = require "skynet"
local Utils = require "utils"
local session_coroutine_id = Utils.get_func_upvalue(skynet.ignoreret, "session_coroutine_id")
local count = 0
for _ in pairs(session_coroutine_id) do
        count = count + 1
end
print(count)

main.go

package main

import (
	"fmt"
	"net"
)

func main() {
	conn, err := net.Dial("tcp", "127.0.0.1:8290")
	if err != nil {
		fmt.Print("err", err)
		return
	}
	content := []byte{0, 0, 0, 0}
	for i := 0; i < 10000; i++ {
		_, err := conn.Write(content)
		if err != nil {
			fmt.Print("err", err)
			return
		}
	}
	fmt.Println("done")
}

orm_array_json.lua

local json = require "json"
local orm  = require "orm.orm"
local resolve = require "orm.typedef"
local define = [[
pictures [number]
]]
local type_list = resolve.parse_string(define)
orm.init(type_list)
local data = orm.create("pictures", {1, 100,})
print(json.encode(data))