[erlang-questions] OTP process startup vs spawn overhead

[Heinrich Venter]

Fun = fun() -> [ Pid ! ok || _ <- lists:seq(1,10000), Pid <-
spawn_link(?MODULE, recv, []) ] end.

This wont work, because spawn_link does not generate a list :)

> Are you running that expression from the shell?
I was executing the tests from the shell yes, but if I do the
following with a compiled function

[ timer:tc(fun() -> [ Pid ! ok || Pid <- [spawn(fun() ->
test_gen:loop() end) || _ <- lists:seq(1,10000)] ] end) || _ <-
lists:seq(1,10)].

I still get the same slow performance.  It must be related to creation
of the fun then.

This gets better results
[ timer:tc(fun() -> [ Pid ! ok || Pid <- [spawn(test_gen, loop, []) ||
_ <- lists:seq(1,10000)] ] end) || _ <- lists:seq(1,10)].

It also shows a bout 45% performance penalty for spawning OTP
processes like mad instead of using spawn(Module, Function, Args).
On the other hand using spawn(Fun) seems to be 4 times slower.  This
is more or less in line with what the efficiency guide says.

It pays to measure :)

Moral of the story: Spawn your workers with spawn(M,F,A) or use OTP
processes if you can afford the slight performance hit and gain a lot
of convenience.

-]-[einrich