File

net.server_epoll: Set minimum wait time to 1ms, matching epoll A timeout value less than 0.001 gets turned into zero on the C side, so epoll_wait() returns instantly and essentially busy-loops up to 1ms, e.g. when a timer event ends up scheduled (0, 0.001)ms into the future. Unsure if this has much effect in practice, but it may waste a small amount of CPU time. How much would depend on how often this ends up happening and how fast the CPU gets trough main loop iterations.

local data = {}
local getinfo = debug.getinfo;
local function linehook(ev, li)
	local S = getinfo(2, "S");
	if S and S.source and S.source:match"^@" then
		local file = S.source:sub(2);
		local lines = data[file];
		if not lines then
			lines = {};
			data[file] = lines;
			for line in io.lines(file) do
				lines[#lines+1] = line;
			end
		end
		io.stderr:write(ev, " ", file, " ", li, " ", lines[li], "\n");
	end
end
debug.sethook(linehook, "l");