# Identical dependency being replaced while importing packages

**URL:** https://discourse.julialang.org/t/identical-dependency-being-replaced-while-importing-packages/39209
**Category:** General Usage
**Tags:** question
**Created:** [May 10, 2020, 4:23am UTC](https://discourse.julialang.org/t/identical-dependency-being-replaced-while-importing-packages/39209 "2020-05-10T04:23:06Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![jishnub](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jishnub/32/33620_2.png) [@jishnub](https://discourse.julialang.org/u/jishnub)
#### Post date: [May 10, 2020, 4:23am UTC](https://discourse.julialang.org/t/identical-dependency-being-replaced-while-importing-packages/39209/1 "2020-05-10T04:23:06Z")

</div>

I am facing an issue that seems to have cropped up suddenly. I am trying to import the packages `JLD2` and `NamedArrays` on a HPC cluster (not sure if this is relevant), and they seem to clash over `DataStructures`. I’m not sure what’s going on and how to resolve this.

If I import `JLD2` before `NamedArrays` I get

```julia
julia> import JLD2

julia> import NamedArrays
┌ Warning: Replacing module `DataStructures`
└ @ Base loading.jl:947

```

whereas if I import them by reversing the sequence I obtain

```julia
julia> import NamedArrays

julia> import JLD2
[Info: Precompiling JLD2 [033835bb-8acc-5ee8-8aae-3f567f8a3819]
┌ Warning: Module DataStructures with build ID 7498601554111257 is missing from the cache.
│ This may mean DataStructures [864edb3b-99cc-5e75-8d2d-829cb0a9cfe8] does not support precompilation but is imported by a module that does.
└ @ Base loading.jl:1016
[Info: Skipping precompilation since __precompile__ (false). Importing JLD2 [033835bb-8acc-5ee8-8aae-3f567f8a3819].

```

This is not happening on my local computer. I am running this on a login node on a single processor, so there’s no race condition.

The relevant lines in `loading.jl` appear to be

```julia
key = PkgId(m, String(nameof(m)))
    if haskey(loaded_modules, key)
        oldm = loaded_modules[key]
        if oldm !== m
            @warn "Replacing module `$(key.name)`"
        end
    end

```

so I check what’s going on

```julia
julia> using JLD2

julia> key = Base.PkgId(JLD2.DataStructures, String(nameof(JLD2.DataStructures)))
DataStructures [864edb3b-99cc-5e75-8d2d-829cb0a9cfe8]

julia> haskey(Base.loaded_modules,key)
true

julia> oldm = Base.loaded_modules[key]
DataStructures

julia> using NamedArrays
┌ Warning: Replacing module `DataStructures`
└ @ Base loading.jl:947

julia> m = Base.loaded_modules[key]
DataStructures

julia> m == oldm
false

```

Why are the modules different? And how can I solve this (hopefully without removing the compile caches altogether, but I’m ok with that if there’s no choice)?

---

<div class="post-metadata">

### Author: ![jishnub](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jishnub/32/33620_2.png) [@jishnub](https://discourse.julialang.org/u/jishnub)
#### Post date: [May 10, 2020, 5:09am UTC](https://discourse.julialang.org/t/identical-dependency-being-replaced-while-importing-packages/39209/2 "2020-05-10T05:09:19Z")

</div>

It appears to have been related to the compile cache. Removing `~/.julia/compiled/v1.4` and precompiling the packages has resolved the issue. Not sure what exactly was resulting in this.