显示谓词子句每个目标的执行时间 [英] Display the execution times for each goal of a predicate clause

问题描述

我想使用 SICStus Prolog 查看谓词目标内的执行时间.

I want to see the execution time inside goals of predicate with SICStus Prolog.

示例:

pred :-
   goal1,
   time,
   goal2,
   time.

go :-
   call(pred).

time_go :-
   go,
   times(go).

预期结果:

?- time_go.
times_go = 1000ms ,   
times_go_goal1 = 500ms,
times_go_goal2 = 500ms

怎么做?

我尝试了 library(timeout) 中的 time_out(:Goal, +Time, -Result) 但我收到了这个错误:

I tried time_out(:Goal, +Time, -Result) from library(timeout) but I got this error:

| ?- time_out(char_code(a,N), T, Res).
! Instantiation error in argument 2 of user:time_out/3
! goal:  time_out(user:char_code(a,_193),_179,_181)

| ?- time_out(char_code(a,N), 1000, Res).
N = 97,
Res = success ? ; % Res=timeout in other example

推荐答案

您可以使用 statistics/2 :

statistics(runtime,[Start|_]),
do_something,
statistics(runtime,[Stop|_]),
Runtime is Stop - Start.

或者，如果您想包括垃圾收集时间，您可以使用 total_runtime 而不是 runtime.Start 和 Stop 以毫秒为单位，但上次我将它与 SICStus 一起使用时，它只返回 10 的倍数.在一个项目中，我们使用了对自定义外部 C 库的调用检索更精细的分辨率.

Alternatively, you can use total_runtime instead of runtime if you want to include time for garbage collection. Start and Stop are measured in milliseconds, but the last time I used it with SICStus it returned only multiple of 10. In a project we used calls to a custom external C library to retrieve a finer resolution.

对time_out/3 的说明:它用于限制目标的运行时间，而不是测量其运行时间.如果目标及时完成，结果为success，如果需要更多时间则中止执行(内部抛出超时异常)，结果为timeout.

A remark to time_out/3: It is used to limit the runtime of a goal, not to measure its runtime. If the goal finishes in time, the result is success, if it needs more time the execution is aborted (internally a timeout exception is thrown) and the result is timeout.

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