Debug Lua Mem

debugmem.lua

function debug_refs()
  local reftable = {}
  local function trace_refs(o, src, src2, src3)
    local typ = type(o)
    if typ == 'number' or typ == 'boolean' or typ == 'string' or typ == 'thread' or typ == 'nil' then return end
    if o == debug_refs or o == reftable or o == trace_refs then return end
    if reftable[o] then return end
    reftable[o] = true
    if src3 then
      src = string.format('%s%s%s', src, src2, tostring(src3))
    elseif src2 then
      src = string.format('%s%s', src, src2)
    end
    local refs = 0
    if typ == 'table' then
      for k,v in pairs(o) do
        trace_refs(k, src, ':', tostring(k))
        trace_refs(v, src, '.', tostring(k))
        refs = refs + 2
      end
      local mt = getmetatable(o)
      if mt then
        trace_refs(mt, src, ':mt')
      end
    elseif typ == 'userdata' then
      local mt = getmetatable(o)
      if mt then
        trace_refs(mt, src, ':mt')
      end
    elseif typ == 'function' then
      local i = 1
      while true do
        local n, v = debug.getupvalue(o, i)
        if not n then break end
        trace_refs(v, src, '.up', i)
        i = i + 1
        refs = refs + 1
      end
      trace_refs(getfenv(o), 'env')
    end
    reftable[o] = { src, refs }
  end

  trace_refs(_G, '_G')
  trace_refs(debug.getregistry(), 'registry')
  for i=0,3 do
    trace_refs(getfenv(i), 'global env')
  end

  local sorted_refs = {}
  local total_refs = 0
  for o,v in pairs(reftable) do
    table.insert(sorted_refs, {o, v[1], v[2]})
    total_refs = total_refs + v[2]
  end
  table.sort(sorted_refs, function(a, b) return a[3] > b[3] end)
  for i=1,100 do
    local o, src, refs = unpack(sorted_refs[i])
    print(string.format('%8d refs\t%s', refs, src))
  end
  print('total refs', total_refs)
end

debug_refs()