-module(processes).
-export([max/1]).

%% max(N)
%%
%% Create N processes then destroy them
%% See how much time this takes
max(N) ->
    Max = erlang:system_info(process_limit),
    RealN = if N > Max -> Max; true -> N end,
    io:format("Max allowed processes: ~p~n", [Max]),
    statistics(runtime),
    statistics(wall_clock),
    L = for(1, RealN, fun() -> spawn(fun() -> wait() end) end),
    {_, Time1} = statistics(runtime),
    {_, Time2} = statistics(wall_clock),
    lists:foreach(fun(Pid) -> Pid ! die end, L),    
    U1 = Time1 * 1000 / RealN,
    U2 = Time2 * 1000 / RealN,
    io:format("Process spawn time=~p (~p) microseconds~n", [U1, U2]).

wait() ->
    receive
	die->
	    void
    end.

for(N, N, F) -> [F()];
for(I, N, F) -> [F()|for(I+1, N, F)].