erlang 列表推导和递归哪个速度快?
程序员文章站
2022-07-15 11:38:43
...
直接上代码:
-module (tl). -export ([t1/0, t2/0]). t1() -> [ X || X <- lists:seq(1, 5000) ]. t2() -> t2(lists:seq(1, 5000)). t2([H|T]) -> H, t2(T); t2([]) -> ok.
tc代码:
%% =================================================================== %% Author xiaotie %% 2015-07-30 %% 单进程循环测试:LoopTimes是循环次数 %% tc:t(Module, Function, ArgsList, LoopTimes). %% 多进程并发测试:SpawnProcessesCount是并发的进程数 %% tc:ct(Module, Function, ArgsList, SpawnProcessesCount). %% =================================================================== -module (tc). -export ([t/4, ct/4]). tc(M, F, A) -> {Microsecond, _} = timer:tc (M, F, A), Microsecond. distribution(List, Aver) -> distribution(List, Aver, 0, 0). distribution([H|T], Aver, Greater, Less) -> case H > Aver of true -> distribution(T, Aver, Greater + 1, Less); false -> distribution(T, Aver, Greater, Less + 1) end; distribution([], _Aver, Greater, Less) -> {Greater, Less}. %% =================================================================== %% test: one process test N times %% =================================================================== t(M, F, A, N) -> {Max, Min, Sum, Aver, Greater, Less} = loop ({M, F, A}, N), io:format ("=====================~n"), io:format ("execute [~p] times of {~p, ~p, ~p}:~n", [N, M, F, A]), io:format ("Maximum: ~p(μs)\t~p(s)~n", [Max, Max / 1000000]), io:format ("Minimum: ~p(μs)\t~p(s)~n", [Min, Min / 1000000]), io:format ("Sum: ~p(μs)\t~p(s)~n", [Sum, Sum / 1000000]), io:format ("Average: ~p(μs)\t~p(s)~n", [Aver, Aver / 1000000]), io:format ("Greater: ~p~nLess: ~p~n", [Greater, Less]), io:format ("=====================~n"). loop({M, F, A}, N) -> loop ({M, F, A}, N, 1, 0, 0, 0, []). loop({M, F, A}, N, I, Max, Min, Sum, List) when N >= I -> Microsecond = tc (M, F, A), NewSum = Sum + Microsecond, if Max == 0 -> NewMax = NewMin = Microsecond; Max < Microsecond -> NewMax = Microsecond, NewMin = Min; Min > Microsecond -> NewMax = Max, NewMin = Microsecond; true -> NewMax = Max, NewMin = Min end, loop ({M, F, A}, N, I + 1, NewMax, NewMin, NewSum, [Microsecond|List]); loop({_M, _F, _A}, N, _I, Max, Min, Sum, List) -> Aver = Sum / N, {Greater, Less} = distribution(List, Aver), {Max, Min, Sum, Aver, Greater, Less}. %% =================================================================== %% Concurrency test: N processes each test one time %% =================================================================== ct(M, F, A, N) -> {Max, Min, Sum, Aver, Greater, Less} = cloop ({M, F, A}, N), io:format ("=====================~n"), io:format ("spawn [~p] processes of {~p, ~p, ~p}:~n", [N, M, F, A]), io:format ("Maximum: ~p(μs)\t~p(s)~n", [Max, Max / 1000000]), io:format ("Minimum: ~p(μs)\t~p(s)~n", [Min, Min / 1000000]), io:format ("Sum: ~p(μs)\t~p(s)~n", [Sum, Sum / 1000000]), io:format ("Average: ~p(μs)\t~p(s)~n", [Aver, Aver / 1000000]), io:format ("Greater: ~p~nLess: ~p~n", [Greater, Less]), io:format ("=====================~n"). cloop({M, F, A}, N) -> CollectorPid = self(), ok = loop_spawn({M, F, A}, CollectorPid, N), collector(0, 0, 0, N, 1, []). loop_spawn({M, F, A}, CollectorPid, N) when N > 0 -> spawn_link(fun() -> worker({M, F, A}, CollectorPid) end), loop_spawn({M, F, A}, CollectorPid, N - 1); loop_spawn(_, _, 0) -> ok. collector(Max, Min, Sum, N, I, List) when N >= I -> receive {result, Microsecond} -> NewSum = Sum + Microsecond, if Max == 0 -> NewMax = NewMin = Microsecond; Max < Microsecond -> NewMax = Microsecond, NewMin = Min; Min > Microsecond -> NewMax = Max, NewMin = Microsecond; true -> NewMax = Max, NewMin = Min end, collector(NewMax, NewMin, NewSum, N, I + 1, [Microsecond|List]) after 10000 -> ok end; collector(Max, Min, Sum, N, _, List) -> Aver = Sum / N, {Greater, Less} = distribution(List, Aver), {Max, Min, Sum, Aver, Greater, Less}. worker({M, F, A}, CollectorPid) -> Microsecond = tc(M, F, A), CollectorPid ! {result, Microsecond}.
结果:
==> etoml (compile) ==> simple_im (compile) Erlang/OTP 18 [erts-7.0] [source] [64-bit] [smp:8:8] [async-threads:10] [kernel-poll:false] Eshell V7.0 (abort with ^G) 1> tc:t(tl, t1, [], 5000). ===================== execute [5000] times of {tl, t1, []}: Maximum: 357(μs) 3.57e-4(s) Minimum: 98(μs) 9.8e-5(s) Sum: 537592(μs) 0.537592(s) Average: 107.5184(μs) 1.075184e-4(s) Greater: 957 Less: 4043 ===================== 2> tc:t(tl, t2, [], 5000). ===================== execute [5000] times of {tl, t2, []}: Maximum: 321(μs) 3.21e-4(s) Minimum: 81(μs) 8.1e-5(s) Sum: 431156(μs) 0.431156(s) Average: 86.2312(μs) 8.62312e-5(s) Greater: 1680 Less: 3320 =====================
上一篇: Django项目的项目准备
下一篇: erlang的消息队列