Run a loop for a set amount of time

[Adi_Rai]

Hi Everyone,

I was converting some MATLAB code to Julia. In MATLAB to run a while loop for a set period is done using tic and toc functions. I was struggling with implementing the same thing in Julia.

My question in short is how to run a while loop for a specific period of time in Julia.

Any help would be appreciated. Thanks.

[jling]

julia> function run(s)
           t = time()
           while time() < t + s
               sleep(0.001)
           end
       end
run (generic function with 1 method)

julia> @time run(0.1)
  0.101925 seconds (231 allocations: 6.766 KiB)

julia> @time run(0.5)
  0.502150 seconds (1.14 k allocations: 34.453 KiB)

julia> @time run(1.2)
  1.200282 seconds (2.75 k allocations: 83.469 KiB)

this is probably close to your tic toc in MATLAB

[Adi_Rai]

That is exactly what I was looking for! Thanks alot.

[sylvaticus]

wondering why allocations depend on s…

[lmiq]

Is it necessary for sleep to allocate?

I was optimizing a complex block of multithreaded code and discovered that sleep was allocating. julia> @btime sleep(0) 1.720 μs (5 allocations: 144 bytes) I was pretty surprised, so checked the source which is basically wait(Timer(sec)), so it’s allocating a mutable struct for that Timer. Is there a more efficient alternative to that to sleep for a very short time? I found a reference to usleep but I’m on Windows so that’s not an option for me. I need a thread to sleep briefly (millisecon…

[ufechner7]

You can use sleep_ms(1) from the package Timers, much more accurate and non-allocating…

[stevengj]

Probably in a real application you wouldn’t call sleep at all—your loop would be doing enough work that the overhead of occasional time calls would be negligible. (If not, you should just check the time every N-th iteration for a sufficiently large N.)