bug: Strings in luajit are infinitely bloated, even if they are not rereferenced in the lua vm

Strings in luajit are infinitely bloated, even if they are not rereferenced in the lua vm. As a result, the memory resources of the nginx process RES are increasing to become larger and larger.

Minimal example code

resty example.lua

`
local function get_memory_usage()
local b = collectgarbage("count") * 1024
return b
end

local my_table = {}  
for i = 1, 10000000 do  
    my_table[i] =  string.rep("A" , 256) .. i  

end

my_table = nil
print("start gc:", "mem:",get_memory_usage())
collectgarbage("collect") 
print("end gc:", "mem:",get_memory_usage())
print("sleep 10m")

print("done")
ngx.sleep(60*10*6)

`

Start by running the minimal resty example.lua and compare collectgarbage("count") before and after the full collection. Investigate how the reported strings affect the nginx process RES after the Lua VM no longer references them. Done means the reported memory growth is explained and the underlying retention behavior is corrected or documented with a reproducible check.