Is there an alternative to debug.sethook()?

I'm trying to add a little extra safety to a sandbox I've created. On top of doing all the ENV changes, I want to limit CPU and memory usage.

This is some quick and simple Lua code that (mostly) accomplishes that:

local stepLimit = 50 --Maximum instructions
local memLimit = 1000 --Max memory in KB
local count = 0 --Counter for the steps


local function checkMem()
	if collectgarbage("count")>memLimit then --If too much mem usage
		error("uses too much memory")
	end
end

local function step()
	checkMem() --check mem usage
	count = count+1
	if count>stepLimit then -- if too much CPU usage
		error("uses too much CPU")
	end
end

local code = loadstring("while wait(1) do print('hi') end") --load a chunk
debug.sethook(step, "", 100) --setup this bit of sandboxy stuff
code() --run

However, Roblox uses a modified version of Lua 5.1.4, which lacks debug.sethook() as a function.

Running this code simply gives: attempt to call field 'sethook' (a nil value) (Commenting out the debug.sethook() line makes the code run, everything else is fine)

So if I cannot use this, how else can I manage memory and CPU?

Thank you to "howmanysmall" on the Lua Learning Discord

Well, rather than be able to set a hook, I can create a thread alongside it.

spawn(function()
	while wait() do
		local MemUsage = collectgarbage("count")/1000 --(/1000 makes it MB which I prefer)
		--print("memUsage:", MemUsage, "(in MB)")
		if (MemUsage) > MemLimit then
			error('{Code abortion}-"Using too much memory"')
		end
	end
end)

Not the best (or even close to it), but it does help.

Still no clue how to handle overusing CPU!