# MPI.jl warning with system provided MPI

**URL:** <https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063>\
**Category:** Julia at Scale\
**Tags:** mpi\
**Created:** [October 19, 2021, 8:39pm UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063 "2021-10-19T20:39:32Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![hideakiv](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hideakiv/32/22193_2.png) [@hideakiv](https://discourse.julialang.org/u/hideakiv)\
**Post date:** [October 19, 2021, 8:39pm UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/1 "2021-10-19T20:39:32Z")

</div>

I am using MPI.jl on an HPC cluster.  
I got a warning

```julia
┌ Warning: You appear to be using MPI.jl with the default MPI binary on a cluster.

│ We recommend using the system-provided MPI, see the Configuration section of the MPI.jl docs.

└ @ MPI ~/.julia/packages/MPI/b7MVG/deps/deps.jl:15

```

so I set up `ENV["JULIA_MPI_BINARY"]="system"` and build MPI.  
Now, I am getting a new warning

```julia
┌ Warning: Error requiring `MPICH_jll` from `MPI`
│ exception =
│ MPICH_jll cannot be loaded: MPI.jl is configured to use the system MPI library

```

Seemingly, this issue occurs when I am using two nodes, but not when I am using one node.  
I would appreciate any hints as to figuring out what might be happening here.

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<div class="post-metadata">

**Author:** ![simonbyrne](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/simonbyrne/32/19_2.png) [@simonbyrne](https://discourse.julialang.org/u/simonbyrne)\
**Post date:** [October 20, 2021, 4:30am UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/2 "2021-10-20T04:30:32Z")

</div>

Can you show the next line of the Warning with the line number?

Also what version of MPI.jl are you using? You can find it by `Pkg.status()`

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<div class="post-metadata">

**Author:** ![hideakiv](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hideakiv/32/22193_2.png) [@hideakiv](https://discourse.julialang.org/u/hideakiv)\
**Post date:** [October 20, 2021, 4:40am UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/3 "2021-10-20T04:40:05Z")

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This is v0.16.1.  
The complete message is

```julia
┌ Warning: Error requiring `MPICH_jll` from `MPI`
│ exception =
│ MPICH_jll cannot be loaded: MPI.jl is configured to use the system MPI library
│ Stacktrace:
│ [1] error(::String) at ./error.jl:33
│ [2] top-level scope at none:1
│ [3] eval at ./boot.jl:331 [inlined]
│ [4] eval at /home/username/.julia/packages/MPI/b7MVG/src/MPI.jl:1 [inlined]
│ [5] (::MPI.var"#3#12")() at /home/username/.julia/packages/Requires/7Ncym/src/require.jl:99
│ [6] err(::Any, ::Module, ::String) at /home/username/.julia/packages/Requires/7Ncym/src/require.jl:47
│ [7] (::MPI.var"#2#11")() at /home/username/.julia/packages/Requires/7Ncym/src/require.jl:98
│ [8] withpath(::Any, ::String) at /home/username/.julia/packages/Requires/7Ncym/src/require.jl:37
│ [9] (::MPI.var"#1#10")() at /home/username/.julia/packages/Requires/7Ncym/src/require.jl:97
│ [10] listenpkg(::Any, ::Base.PkgId) at /home/username/.julia/packages/Requires/7Ncym/src/require.jl:20
│ [11] macro expansion at /home/username/.julia/packages/Requires/7Ncym/src/require.jl:95 [inlined]
│ [12] __init__ deps() at /home/username/.julia/packages/MPI/b7MVG/deps/deps.jl:14
│ [13] __init__ () at /home/username/.julia/packages/MPI/b7MVG/src/MPI.jl:67
│ [14] _include_from_serialized(::String, ::Array{Any,1}) at ./loading.jl:697
│ [15] _require_search_from_serialized(::Base.PkgId, ::String) at ./loading.jl:782
│ [16] _tryrequire_from_serialized(::Base.PkgId, ::UInt64, ::Nothing) at ./loading.jl:712
│ [17] _require_from_serialized(::String) at ./loading.jl:744
│ [18] _require(::Base.PkgId) at ./loading.jl:1040
│ [19] require(::Base.PkgId) at ./loading.jl:928
│ [20] require(::Module, ::Symbol) at ./loading.jl:923
│ [21] include(::Function, ::Module, ::String) at ./Base.jl:380
│ [22] include(::Module, ::String) at ./Base.jl:368
│ [23] exec_options(::Base.JLOptions) at ./client.jl:296
│ [24] _start() at ./client.jl:506
└ @ Requires ~/.julia/packages/Requires/7Ncym/src/require.jl:49

```

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<div class="post-metadata">

**Author:** ![simonbyrne](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/simonbyrne/32/19_2.png) [@simonbyrne](https://discourse.julialang.org/u/simonbyrne)\
**Post date:** [October 20, 2021, 6:07pm UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/4 "2021-10-20T18:07:25Z")

</div>

Are you manually loading MPICH\_jll somewhere?

Maybe try using the most recent version of MPI.jl?

---

<div class="post-metadata">

**Author:** ![hideakiv](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hideakiv/32/22193_2.png) [@hideakiv](https://discourse.julialang.org/u/hideakiv)\
**Post date:** [October 21, 2021, 6:09pm UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/5 "2021-10-21T18:09:55Z")

</div>

updating the most recent version created more issues…  
How can I check whether I am manually loading MPICH\_jll?

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<div class="post-metadata">

**Author:** ![simonbyrne](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/simonbyrne/32/19_2.png) [@simonbyrne](https://discourse.julialang.org/u/simonbyrne)\
**Post date:** [October 21, 2021, 6:45pm UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/6 "2021-10-21T18:45:31Z")

</div>

Is there any mention of MPICH\_jll anywhere in the code?

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<div class="post-metadata">

**Author:** ![hideakiv](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/hideakiv/32/22193_2.png) [@hideakiv](https://discourse.julialang.org/u/hideakiv)\
**Post date:** [October 21, 2021, 6:52pm UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/7 "2021-10-21T18:52:59Z")

</div>

No… I looked at all dependent packages.

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<div class="post-metadata">

**Author:** ![simonbyrne](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/simonbyrne/32/19_2.png) [@simonbyrne](https://discourse.julialang.org/u/simonbyrne)\
**Post date:** [October 25, 2021, 6:06pm UTC](https://discourse.julialang.org/t/mpi-jl-warning-with-system-provided-mpi/70063/8 "2021-10-25T18:06:01Z")

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> [@hideakiv](#):
>
> Seemingly, this issue occurs when I am using two nodes, but not when I am using one node.  
> I would appreciate any hints as to figuring out what might be happening here.

My only idea is that one node is configured differently: are both nodes set up to use the same Pkg directory and Julia environment?