could not load symbol error for LU or QR factorizations on Julia 1.13 or newer with multithreading

[kpobrien]

Hi,

I'm seeing an error when trying to perform LU or QR factorization on multiple threads in parallel with Julia 1.13. I don't see the error on 1.12 or earlier. The error only occurs the first time the code below (a MWE) is called.

Julia 1.13

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.13.0-alpha2 (2025-11-30)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org release
|__/                   |

julia> using LinearAlgebra, SparseArrays

julia> Base.@sync for i in 1:2
           Base.Threads.@spawn lu(sprand(Complex{Float64},2,2,1.0))
       end
ERROR: TaskFailedException

    nested task error: could not load symbol "umfpack_zl_defaults":
    /home/kevin/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/bin/../lib/julia/libjulia-internal.so.1.13: undefined symbol: umfpack_zl_defaults
    Stacktrace:
     [1] umfpack_zl_defaults
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/SparseArrays/src/solvers/wrappers.jl:2474 [inlined]
     [2] get_umfpack_control
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/SparseArrays/src/solvers/umfpack.jl:1040 [inlined]
     [3] lu
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/SparseArrays/src/solvers/umfpack.jl:369 [inlined]
     [4] (::var"#2#3")()
       @ Main ./REPL[1]:2
Stacktrace:
 [1] sync_end(c::Channel{Any})
   @ Base ./task.jl:630
 [2] top-level scope
   @ REPL[1]:1
 [3] macro expansion
   @ task.jl:663 [inlined]

If I call a function first that loads the library, I don't see the error.

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.13.0-alpha2 (2025-11-30)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org release
|__/                   |

julia> using LinearAlgebra, SparseArrays

julia> SparseArrays.UMFPACK.get_umfpack_control(Complex{Float64},Int64);

julia> Base.@sync for i in 1:2
           Base.Threads.@spawn lu(sprand(Complex{Float64},2,2,1.0))
       end

julia> 

Similar behavior for QR factorization and on nightly. No error on 1.12.

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.13.0-alpha2 (2025-11-30)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org release
|__/                   |

julia> using LinearAlgebra, SparseArrays

julia> Base.@sync for i in 1:2
           Base.Threads.@spawn qr(sprand(Complex{Float64},2,2,1.0))
       end
ERROR: TaskFailedException

    nested task error: could not load symbol "SuiteSparseQR_C":
    /home/kevin/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/bin/../lib/julia/libjulia-internal.so.1.13: undefined symbol: SuiteSparseQR_C
    Stacktrace:
     [1] SuiteSparseQR_C(ordering::Int32, tol::Float64, econ::Int64, getCTX::Int64, A::SparseArrays.CHOLMOD.Sparse{…}, Bsparse::Ptr{…}, Bdense::Ptr{…}, Zsparse::Ptr{…}, Zdense::Ptr{…}, R::Base.RefValue{…}, E::Base.RefValue{…}, H::Base.RefValue{…}, HPinv::Base.RefValue{…}, HTau::Base.RefValue{…}, cc::Base.RefValue{…})
       @ SparseArrays.LibSuiteSparse ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/SparseArrays/src/solvers/wrappers.jl:2167
     [2] _qr!(ordering::Int32, tol::Float64, econ::Int64, getCTX::Int64, A::SparseArrays.CHOLMOD.Sparse{…}, Bsparse::Ptr{…}, Bdense::Ptr{…}, Zsparse::Ptr{…}, Zdense::Ptr{…}, R::Base.RefValue{…}, E::Base.RefValue{…}, H::Base.RefValue{…}, HPinv::Base.RefValue{…}, HTau::Base.RefValue{…})
       @ SparseArrays.SPQR ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/SparseArrays/src/solvers/spqr.jl:55
     [3] qr(A::SparseMatrixCSC{ComplexF64, Int64}; tol::Float64, ordering::Int32)
       @ SparseArrays.SPQR ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/SparseArrays/src/solvers/spqr.jl:203
     [4] qr(A::SparseMatrixCSC{ComplexF64, Int64})
       @ SparseArrays.SPQR ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/SparseArrays/src/solvers/spqr.jl:195
     [5] (::var"#2#3")()
       @ Main ./REPL[1]:2
Stacktrace:
 [1] sync_end(c::Channel{Any})
   @ Base ./task.jl:630
 [2] top-level scope
   @ REPL[1]:1
 [3] macro expansion
   @ task.jl:663 [inlined]
Some type information was truncated. Use `show(err)` to see complete types.

Interestingly, I don't see the error with KLU.jl.

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.13.0-alpha2 (2025-11-30)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org release
|__/                   |

julia> using LinearAlgebra, SparseArrays, KLU

julia> Base.@sync for i in 1:2
           Base.Threads.@spawn klu(sprand(Complex{Float64},2,2,1.0))
       end

julia> 

If this is a bug in Julia, let me know and I can make an issue in that repo instead.

[kpobrien]

Also, the above error occurs on Linux. I also ran the same tests on Windows and don't get any errors.

[ViralBShah]

Would love to get a bisect (but not sure how easy it is to do that).

[kpobrien]

Thanks Viral, I attempted a crude bisect using Juliaup but wasn't able to find a 1.13 version old enough to not have the error (probably due to older versions getting deleted).

This was the test:

using LinearAlgebra, SparseArrays
Base.@sync for i in 1:2
    Base.Threads.@spawn lu(sprand(Complex{Float64},2,2,1.0))
end

and the results:

errors
https://github.com/JuliaLang/julia/pull/60166
Version 1.13.0-DEV.1420 (2025-11-18)

errors
https://github.com/JuliaLang/julia/pull/60070
Version 1.14.0-DEV.38 (2025-11-07)

errors
https://github.com/JuliaLang/julia/pull/59765
Version 1.13.0-DEV.1360 (2025-10-21)

errors
https://github.com/JuliaLang/julia/pull/59873
Version 1.13.0-DEV.1318 (2025-10-17)

errors
https://github.com/JuliaLang/julia/pull/59847
Version 1.13.0-DEV.1326 (2025-10-17)

errors
https://github.com/JuliaLang/julia/pull/59849
Version 1.13.0-DEV.1318 (2025-10-16)

errors
https://github.com/JuliaLang/julia/pull/59848
Version 1.13.0-DEV.1317 (2025-10-15)

errors
https://github.com/JuliaLang/julia/pull/59840
Version 1.13.0-DEV.1309 (2025-10-14)

errors
https://github.com/JuliaLang/julia/pull/59832
Version 1.13.0-DEV.1300 (2025-10-14)

errors
https://github.com/JuliaLang/julia/pull/59827
Version 1.13.0-DEV.1301 (2025-10-14)

errors
https://github.com/JuliaLang/julia/pull/59651
Version 1.14.0-DEV.37 (2025-11-05)

Do you know if there is an easier way to bisect older versions than building Julia?

Adding to the confusion, I see this error with Julia 1.13 on Arch (tested on multiple machines) but not on Ubuntu (tested Ubuntu 24.04.3 LTS).

[kpobrien]

Scratch that comment about only seeing it on Arch and not Ubuntu. I was only using 1 thread. Switching to -t auto with 4 threads and I see the error on Ubuntu also.

[kpobrien]

I did the bisection and the bug was introduced by "Convert remaining JLL stdlibs to LazyLibraries" JuliaLang/julia@e984c57

That makes sense since this looks like a race condition with loading the library. It happens for more libraries than I realized (and I believe is a Julia issue not a SparseArrays.jl issue). For example, BLAS:

julia> using LinearAlgebra

julia> Base.@sync for i in 1:2
           Base.Threads.@spawn zeros(10,10)*zeros(10,10)
       end
ERROR: TaskFailedException

    nested task error: could not load symbol "dgemm_64_":
    /home/kevin/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/bin/../lib/julia/libjulia-internal.so.1.13: undefined symbol: dgemm_64_
    Stacktrace:
     [1] gemm!(transA::Char, transB::Char, alpha::Float64, A::Matrix{…}, B::Matrix{…}, beta::Float64, C::Matrix{…})
       @ LinearAlgebra.BLAS ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/blas.jl:1652
     [2] gemm_wrapper!
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/matmul.jl:905 [inlined]
     [3] _syrk_herk_gemm_wrapper!
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/matmul.jl:531 [inlined]
     [4] generic_matmatmul_wrapper!(C::Matrix{…}, tA::Char, tB::Char, A::Matrix{…}, B::Matrix{…}, α::Bool, β::Bool, val::Val{…})
       @ LinearAlgebra ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/matmul.jl:511
     [5] _mul!
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/matmul.jl:333 [inlined]
     [6] mul!
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/matmul.jl:302 [inlined]
     [7] mul!
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/matmul.jl:270 [inlined]
     [8] *
       @ ~/.julia/juliaup/julia-1.13.0-alpha2+0.x64.linux.gnu/share/julia/stdlib/v1.13/LinearAlgebra/src/matmul.jl:141 [inlined]
     [9] (::var"#2#3")()
       @ Main ./REPL[1]:2
Stacktrace:
 [1] sync_end(c::Channel{Any})
   @ Base ./task.jl:630
 [2] top-level scope
   @ REPL[1]:1
 [3] macro expansion
   @ task.jl:663 [inlined]
Some type information was truncated. Use `show(err)` to see complete types.

[ViralBShah]

@KristofferC @vtjnash

[KristofferC]

We should open an issue on the julia repo with this.

[kpobrien]

Thanks! I created an issue in the Julia repo JuliaLang/julia#60378 .