# Stucked at Found FFTW wisdom at C:\\Users\\Administrator\\.julia\\scratchspaces\\30eb0fb0-5147-11e9-3356-d75b018717ce\\lunacache\\FFTWcache\_1threads

**URL:** https://discourse.julialang.org/t/stucked-at-found-fftw-wisdom-at-c-users-administrator-julia-scratchspaces-30eb0fb0-5147-11e9-3356-d75b018717ce-lunacache-fftwcache-1threads/130086
**Category:** New to Julia
**Tags:** question
**Created:** [June 20, 2025, 11:57pm UTC](https://discourse.julialang.org/t/stucked-at-found-fftw-wisdom-at-c-users-administrator-julia-scratchspaces-30eb0fb0-5147-11e9-3356-d75b018717ce-lunacache-fftwcache-1threads/130086 "2025-06-20T23:57:11Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![jiahui](https://avatars.discourse-cdn.com/v4/letter/j/a88e57/32.png) [@jiahui](https://discourse.julialang.org/u/jiahui)
#### Post date: [June 20, 2025, 11:57pm UTC](https://discourse.julialang.org/t/stucked-at-found-fftw-wisdom-at-c-users-administrator-julia-scratchspaces-30eb0fb0-5147-11e9-3356-d75b018717ce-lunacache-fftwcache-1threads/130086/1 "2025-06-20T23:57:11Z")

</div>

Hello,

I’m using Luna package to simulate the pulse propogation in a fiber with simple code:  
using Luna  
output = prop\_capillary(125e-6, 3, :He, 1; λ0=800e-9, energy=120e-6, τfwhm=10e-15, λlims=(150e-9, 4e-6), trange=1e-12)  
But when running, it stuck at  
Found FFTW wisdom at C:\Users\Administrator.julia\scratchspaces\30eb0fb0-5147-11e9-3356-d75b018717ce\lunacache\FFTWcache\_1threads

 ![image](https://global.discourse-cdn.com/julialang/original/3X/a/b/ab4a66852699da1a8dfc7e0dbbc171d8520b54a8.png)

---

<div class="post-metadata">

### Author: ![ederag](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ederag/32/4106_2.png) [@ederag](https://discourse.julialang.org/u/ederag)
#### Post date: [June 21, 2025, 8:29am UTC](https://discourse.julialang.org/t/stucked-at-found-fftw-wisdom-at-c-users-administrator-julia-scratchspaces-30eb0fb0-5147-11e9-3356-d75b018717ce-lunacache-fftwcache-1threads/130086/2 "2025-06-21T08:29:47Z")

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Confirmed, it took more than a minute to finish here,  
which is quite long for an example, so it might be worth [reporting](https://github.com/LupoLab/Luna.jl/issues/new/choose).

```julia-repl
julia> output = prop_capillary(125e-6, 3, :He, 1; λ0=800e-9, energy=120e-6, τfwhm=10e-15, λlims=(150e-9, 4e-6), trange=1e-12)
[ Info: X+Y polarisation not required.                                                                                                             
[ Info: Freq limits 0.07 - 2.00 PHz                                                                                                                
[ Info: Samples needed: 11991.70, samples: 16384, δt = 83.39 as                                                                                    
[ Info: Requested time window: 1000.0 fs, actual time window: 1366.3 fs                                                                            
[ Info: Grid: samples 8192 / 16384, ωmax 1.88e+16 / 3.77e+16                                                                                       
[ Info: Using PPT ionisation rate.                                                                                                                 
[ Info: Found cached PPT rate for 24.59 eV, 800.0 nm                                                                                               
[ Info: Using mode-averaged propagation.                                                                                                           
[ Info: No FFTW wisdom found                                                                                                                       
[ Info: FFTW wisdom saved to /usr/local/build/julia/depot/scratchspaces/30eb0fb0-5147-11e9-3356-d75b018717ce/lunacache/FFTWcache_56threads         
[ Info: Found FFTW wisdom at /usr/local/build/julia/depot/scratchspaces/30eb0fb0-5147-11e9-3356-d75b018717ce/lunacache/FFTWcache_56threads         
[ Info: FFTW wisdom saved to /usr/local/build/julia/depot/scratchspaces/30eb0fb0-5147-11e9-3356-d75b018717ce/lunacache/FFTWcache_56threads         
[ Info: Starting propagation                                                                                                                       
[ Info: Propagation finished in 0.600 seconds, 367 steps                                                                                           
MemoryOutput["simulation_type", "dumps", "meta", "Eω", "prop_capillary_args", "grid", "stats", "z"]   

```

The second run is much faster, probably because the FFTW plan has been created.  
The output is almost the same, with an additional "FFTW wisdom saved " line:

```julia-repl
julia> output = prop_capillary(125e-6, 3, :He, 1; λ0=800e-9, energy=120e-6, τfwhm=10e-15, λlims=(150e-9, 4e-6), trange=1e-12)
[ Info: X+Y polarisation not required.                                                                                                             
[ Info: Freq limits 0.07 - 2.00 PHz                                                                                                                
[ Info: Samples needed: 11991.70, samples: 16384, δt = 83.39 as                                                                                    
[ Info: Requested time window: 1000.0 fs, actual time window: 1366.3 fs                                                                            
[ Info: Grid: samples 8192 / 16384, ωmax 1.88e+16 / 3.77e+16                                                                                       
[ Info: Using PPT ionisation rate.                                                                                                                 
[ Info: Found cached PPT rate for 24.59 eV, 800.0 nm                                                                                               
[ Info: Using mode-averaged propagation.                                                                                                           
[ Info: Found FFTW wisdom at /usr/local/build/julia/depot/scratchspaces/30eb0fb0-5147-11e9-3356-d75b018717ce/lunacache/FFTWcache_56threads         
[ Info: FFTW wisdom saved to /usr/local/build/julia/depot/scratchspaces/30eb0fb0-5147-11e9-3356-d75b018717ce/lunacache/FFTWcache_56threads         
[ Info: Found FFTW wisdom at /usr/local/build/julia/depot/scratchspaces/30eb0fb0-5147-11e9-3356-d75b018717ce/lunacache/FFTWcache_56threads         
[ Info: FFTW wisdom saved to /usr/local/build/julia/depot/scratchspaces/30eb0fb0-5147-11e9-3356-d75b018717ce/lunacache/FFTWcache_56threads         
[ Info: Starting propagation                                                                                                                       
[ Info: Propagation finished in 0.523 seconds, 367 steps                                                                                           
MemoryOutput["simulation_type", "dumps", "meta", "Eω", "prop_capillary_args", "grid", "stats", "z"]

```

```julia-repl
julia> versioninfo()
  Julia Version 1.10.9
  OS: Linux (x86_64-suse-linux)                                                                                                                    
  CPU: 16 × AMD Ryzen 9 9950X3D 16-Core Processor
Threads: 14 default, 0 interactive, 7 GC (on 16 virtual cores) 

```

---

<div class="post-metadata">

### Author: ![chrisbrahms](https://avatars.discourse-cdn.com/v4/letter/c/c0e974/32.png) [@chrisbrahms](https://discourse.julialang.org/u/chrisbrahms)
#### Post date: [June 21, 2025, 8:06pm UTC](https://discourse.julialang.org/t/stucked-at-found-fftw-wisdom-at-c-users-administrator-julia-scratchspaces-30eb0fb0-5147-11e9-3356-d75b018717ce-lunacache-fftwcache-1threads/130086/3 "2025-06-21T20:06:00Z")

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Hi! Sorry to hear you’re having issues with Luna. The problem you’re running into here is probably a stale `pidlock` around the FFTW cache files. If I’m right, you should be able to fix it by using the `Utils.clear_cache()` function within Luna:

```julia
using Luna
Utils.clear_cache()

```

We actually recently [fixed this issue](https://github.com/LupoLab/Luna.jl/pull/380), we just haven’t released a new version yet.

If this doesn’t fix it, best to open an issue over at [GitHub - LupoLab/Luna.jl: Nonlinear optical pulse propagator](http://github.com/LupoLab/Luna) and we’ll deal with it in more detail.