1msのtimerで実質2ms待ちになる調査

timer_test.erl

-module(timer_test).

-export([test/2]).

test(Wait, Count) ->
    Begin = erlang:timestamp(),
    wait_repeat(Wait, Count),
    End = erlang:timestamp(),
    DiffUsec = timer:now_diff(End, Begin),
    DiffSec = DiffUsec / 1000 / 1000,
    io:format("~p counts in ~p sec, ~p count/sec~n", [Count, DiffSec, Count/DiffSec]).

wait_repeat(_Wait, 0) ->
    ok;
wait_repeat(Wait, N) ->
    timer:sleep(Wait),
    wait_repeat(Wait, N-1).

erl 上で以下で実行。

1> c(timer_test).
{ok,timer_test}
2> timer_test:test(1,1000).
1000 counts in 2.001901 sec, 499.52520129616795 count/sec
ok

See Measure Elapsed Time at http://erlang.org/doc/apps/erts/time_correction.html#how-to-work-with-the-new-api