# Long compilation time of own code
**URL:** https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618
**Category:** General Usage
**Tags:** compilation
**Created:** [January 27, 2023, 9:54am UTC](https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618 "2023-01-27T09:54:00Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Philippe\_Maincon1](https://discourse.julialang.org/u/Philippe_Maincon1)
#### Post date: [January 27, 2023, 9:54am UTC](https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618/1 "2023-01-27T09:54:00Z")
I am getting a very long TTFX on my own code. This is new territory for me. I profiled the compilation and first run, and the profiler reports large amounts of time spent on the call `value_∂{1,Ny}(...)` (which does perfectly fine in other settings), and I start throwing hypotheses around (see below).
```julia
function addin!(out::OUTstaticΛXU,asm,iele,scale,eleobj::E,Λ,X,U,A, t,γ,dbg) where{E}
# compile-time stuff (I hope)
Nx,Nu = getndof(E,:X),getndof(E,:U)
Ny = 2Nx+Nu # Y=[Λ;X;U] ments...
ΔY = variate{2,Ny}(δ{1,Ny,𝕣}())
iλ = SVector{nX}(1:nX)
ix = nX .+SVector{nX}(1:nX)
iu = nX+nX .+SVector{nU}(1:nU)
ΔΛ,ΔX,ΔU = view(ΔY,iλ),view(ΔY,ix),view(ΔY,iu)
# run-time stuff
L = scaledlagrangian(scale,eleobj, Λ+ΔΛ, (∂0(X)+ΔX,),(∂0(U)+ΔU,),A, t,γ,dbg)
Ly,Lyy = value_∂{1,Ny}(∂{2,Ny}(L))
addtoarray!(out.Ly ,asm[1],iele,Ly )
addtoarray!(out.Lyy,asm[2],iele,Lyy)
end
```
**Hypothesis 1** : This is because of something unclear with types which gives the compiler a hard time to generate typestable code. By design all the code in the first half of the function should evaluate at compile time. Note how `Nx` and `Ne` are function of type `E`, and everything else down to `ΔΛ,ΔX,ΔU` is computed from these values. But is this code actualy evaluated at compile time? Is this evaluation hard on the compiler? Should I be using a `@generated` function to explicitly require this computation to be done once and for all?
**Hypothesis 2** : I known that `scaledlagrangian` calls some type unstable code. I know how to fix this, but I wonder, is there any way type instability can make _compiling_ harder?
**Question** : where can I read up on the strategies to profile the compilation process?
**Question** : I tried to use `@code_warntype` on this function. Because its hard to generate all the inputs for the function, I would prefer to do this inside the calling program, not from the REPL. Of course the macro’s full name `InteractiveUtils.@code_warntype` gave me a warning of what was to come. Is there any way around this?
---
### Author:  [@fatteneder](https://discourse.julialang.org/u/fatteneder)
#### Post date: [January 27, 2023, 11:08am UTC](https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618/2 "2023-01-27T11:08:31Z")
> [@Philippe\_Maincon1](#):
>
> Hypothesis 1
Check by calling your function with `@code_typed` and see if you find `Core.Const` in the lines for which you expect compile time evaluation.
---
### Author:  [@lmiq](https://discourse.julialang.org/u/lmiq)
#### Post date: [January 27, 2023, 11:10am UTC](https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618/3 "2023-01-27T11:10:28Z")
> [@Philippe\_Maincon1](#):
>
> ```julia
> iλ = SVector{nX}(1:nX)
> ix = nX .+SVector{nX}(1:nX)
> iu = nX+nX .+SVector{nU}(1:nU)
>
> ```
How large are nX, nU and other sizes of these SVectors? SVectors with large sizes (\> ~50) take a long time to compile (and are not recommended in general).
---
### Author:  [@Philippe\_Maincon1](https://discourse.julialang.org/u/Philippe_Maincon1)
#### Post date: [January 27, 2023, 11:31am UTC](https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618/4 "2023-01-27T11:31:16Z")
They are small. Actual 2 to 4 in the case that gives me looong compilation.
---
### Author:  [@Philippe\_Maincon1](https://discourse.julialang.org/u/Philippe_Maincon1)
#### Post date: [January 27, 2023, 11:33am UTC](https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618/5 "2023-01-27T11:33:56Z")
Great tip! I will work on this.
---
### Author:  [@Philippe\_Maincon1](https://discourse.julialang.org/u/Philippe_Maincon1)
#### Post date: [January 27, 2023, 12:24pm UTC](https://discourse.julialang.org/t/long-compilation-time-of-own-code/93618/6 "2023-01-27T12:24:34Z")
…and I think you are spot on, @Imiq. The compiler seems to choke on `Ny = 14`, and I have a 14x14 `SMatrix`…
Thanks a bunch, and I take note of @fattenedders tip on `@code_type`.
Thank you both!