# Time needed to perform a complete loop
**URL:** https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494
**Category:** General Usage
**Tags:** loops, time
**Created:** [July 3, 2020, 9:04pm UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494 "2020-07-03T21:04:16Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@sergevic](https://discourse.julialang.org/u/sergevic)
#### Post date: [July 3, 2020, 9:04pm UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/1 "2020-07-03T21:04:16Z")
I want to measure the total amount of time nedded to perform a complete loop. I tried
```julia
@time for i in 1:10000
...
...
end
```
and it returned `.988083 seconds (57.58 M allocations: 39.867 GiB, 0.14% gc time)` when the code ran about 15 minutes to complete the loop and not 0.988083 seconds as indicated. How can I measure time correctly?
---
### Author:  [@tim.holy](https://discourse.julialang.org/u/tim.holy)
#### Post date: [July 3, 2020, 10:16pm UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/2 "2020-07-03T22:16:20Z")
Tell us what’s in the `...`? Normally what you did should work fine.
---
### Author:  [@sergevic](https://discourse.julialang.org/u/sergevic)
#### Post date: [July 3, 2020, 10:30pm UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/3 "2020-07-03T22:30:31Z")
The loop calls a lot of functions I created outside of the loop and a dataset I have ☹ ☹ Since the code with the functions is large, I thought that putting just the command I’m using to measure time would be enough to know if I’m using the right command or placing wrongly `@time` ☹
---
### Author:  [@tim.holy](https://discourse.julialang.org/u/tim.holy)
#### Post date: [July 3, 2020, 10:32pm UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/4 "2020-07-03T22:32:08Z")
It should all be fine unless you have `@async`s or threads or whatever. It’s easy to convince yourself that this should work fine:
```julia
julia> @time for i = 1:3
sleep(1)
end
3.006142 seconds (15 allocations: 432 bytes)
```
So there has to be something else going on.
---
### Author:  [@sergevic](https://discourse.julialang.org/u/sergevic)
#### Post date: [July 3, 2020, 10:34pm UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/5 "2020-07-03T22:34:47Z")
Ah thanks @tim.holy! Will check my code then
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [July 4, 2020, 12:29am UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/6 "2020-07-04T00:29:06Z")
`@time` often seems to miss compilation time, at least in generated functions:
```julia
julia> @generated function slow_to_compile(x)
sleep(10)
:(x)
end
slow_to_compile (generic function with 1 method)
julia> t0 = time(); @time for i ∈ 1:3
sleep(slow_to_compile(i))
end; time() - t0
6.009163 seconds (15 allocations: 432 bytes)
16.032392978668213
julia> versioninfo()
Julia Version 1.6.0-DEV.355
Commit 955beb6a91* (2020-07-02 10:28 UTC)
```
---
### Author:  [@Mason](https://discourse.julialang.org/u/Mason)
#### Post date: [July 4, 2020, 1:03am UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/7 "2020-07-04T01:03:13Z")
This is a big of a tangent, but you shouldn’t be doing heavy computations in a globally scoped `for` loop as this will be quite bad for performance and memory usage. Consider using a `let` block or a function (and avoid global variables).
---
### Author:  [@sergevic](https://discourse.julialang.org/u/sergevic)
#### Post date: [July 4, 2020, 1:08am UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/8 "2020-07-04T01:08:24Z")
Ok 🙂 Thanks for your help 🙂 I.m trying to see if I can measure the exact time with another command 🙂
---
### Author:  [@Skoffer](https://discourse.julialang.org/u/Skoffer)
#### Post date: [July 4, 2020, 3:52am UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/9 "2020-07-04T03:52:20Z")
Just out of curiosity, are you using Juno? I saw it sometimes in Juno, that output of @time is being partially “eaten” in console, I guess it’s some weird bug.
---
### Author:  [@baggepinnen](https://discourse.julialang.org/u/baggepinnen)
#### Post date: [July 4, 2020, 5:54am UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/10 "2020-07-04T05:54:36Z")
[https://github.com/JuliaLang/julia/blob/66f41c58683d68b43ad0a2a9d8d605de72ca0de9/base/timing.jl#L171](https://github.com/JuliaLang/julia/blob/66f41c58683d68b43ad0a2a9d8d605de72ca0de9/base/timing.jl#L171)
---
### Author:  [@sergevic](https://discourse.julialang.org/u/sergevic)
#### Post date: [July 4, 2020, 11:56pm UTC](https://discourse.julialang.org/t/time-needed-to-perform-a-complete-loop/42494/11 "2020-07-04T23:56:06Z")
Yes I’m using Juno, indeed!