hnakamur · August 28, 2012 22:47 · Aug 28, 2012
diff --git a/processes.erl b/processes.erl
@@ -0,0 +1,56 @@
+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),
+    io:format("Maximum allowed processes:~p~n", [Max]),
+    statistics(wall_clock),
+    L = for(1, N, fun() -> spawn(fun() -> wait() end) end),
+    {_, Time} = statistics(wall_clock),
+    lists:foreach(fun(Pid) -> Pid ! die end, L),    io:format("Elapsed time=~p seconds~n", [Time / 1000.0]).
+
+wait() ->
+    receive
+        die -> void
+    end.
+
+for(N, N, F) -> [F()];
+for(I, N, F) -> [F()|for(I+1, N, F)].
+
+
+%% Results on Macbook Pro Retina 2012
+%% CPU: Intel Core i7 2.6 GHz
+%% Mem: 16GB 1600 MHz DDR3
+%%
+%% sh-3.2$ erl +P 2000000
+%% Erlang R15B01 (erts-5.9.1) [source] [64-bit] [smp:8:8] [async-threads:0] [hipe] [kernel-poll:false] [dtrace]
+%% 
+%% Eshell V5.9.1  (abort with ^G)
+%% 1> c(processes).
+%% {ok,processes}
+%% 2> processes:max(50000).
+%% Maximum allowed processes:2000000
+%% Elapsed time=0.135 seconds
+%% ok
+%% 3> processes:max(100000).
+%% Maximum allowed processes:2000000
+%% Elapsed time=0.282 seconds
+%% ok
+%% 4> processes:max(200000).
+%% Maximum allowed processes:2000000
+%% Elapsed time=0.535 seconds
+%% ok
+%% 5> processes:max(500000).
+%% Maximum allowed processes:2000000
+%% Elapsed time=1.444 seconds
+%% ok
+%% 6> processes:max(1000000).
+%% Maximum allowed processes:2000000
+%% Elapsed time=3.123 seconds
+%% ok
+%% 7>