Erlang script to show used vs. allocated carrier sizes to find impact of memory fragmentation

find_fragmentation.erl

f().

Str = fun(X) -> io_lib:format("~p", [X]) end.

Percent = fun
  (A, 0) -> "100%";
  (A, B) -> [Str(round(100*A/B)), "%"]
end.

Get = fun
  (undefined, _Key) -> 0;
  (Info, Key) ->
    element(2, lists:keyfind(Key, 1, Info))
end.

GetAlloc = fun
  (undefined)  -> 0;
  (List) -> element(3, hd(List))
end.

Allocators = [sys_alloc, temp_alloc, sl_alloc, std_alloc, ll_alloc,
  eheap_alloc, ets_alloc, fix_alloc, literal_alloc, exec_alloc,
  binary_alloc, driver_alloc, mseg_alloc].

lists:foreach(fun(Alloc) ->
  Info = (catch erlang:system_info({allocator, Alloc})),
  if is_list(Info) ->
    {Allocated, Used, Calls} = lists:foldl(
      fun({instance, _Nr, Stats}, {Al, Us, Ca}) ->
        Mbcs = proplists:get_value(mbcs, Stats),
        Allocated = Get(Mbcs, carriers_size),
        Used = case lists:keyfind(blocks, 1, proplists:get_value(mbcs, Stats, [])) of
          false -> Get(Mbcs, blocks_size);
          {blocks, _, _, _} -> Get(Mbcs, blocks_size);
          {blocks, List} -> lists:foldl(fun({_, Other}, Sum) -> Sum + Get(Other, size) end, 0, List)
        end,
        Calls = GetAlloc(proplists:get_value(calls, Stats)),
        {Allocated + Al, Used + Us, Calls + Ca};
        (_, {Al, Us, Ca}) -> {Al, Us, Ca}
      end,
      {0, 0, 0},
      Info
    ),
    Waste = Allocated - Used,
    io:format(
      "~-14s got ~10s used of ~10s alloc (~4s) = ~10s waste @ ~10s calls~n",
      [Alloc, Str(Used), Str(Allocated), Percent(Used, Allocated), Str(Waste), Str(Calls)]
    );
  true ->
    io:format("~-14s is disabled~n", [Alloc])
  end
end, Allocators).