Lua表预分配：一次到位的容量思路

-- 错误：循环内即建即弃，回收器天天加班
for _, row in pairs(rows) do
    local tmp = {}
    pack(row, tmp)
    send(tmp)
end

local pool = {}
local function acquire()
    local t = table.remove(pool)
    if t == nil then
        t = {}
    end
    return t
end
local function release(t)
    for k in pairs(t) do
        t[k] = nil
    end
    table.insert(pool, t)
end
local t = acquire()
t[1], t[2] = "a", "b"
release(t)