Two calls needed to pyimport a module in Julia, the first one crashes

[gvanuxem]

Affects: PythonCall

I installed sagelib using CondaPkg in Julia: pkg> conda add sagelib

But importing it requires two calls for sage.all. Here is a Julia session:

┌──(greg㉿ellipse)-[~]
└─$ julia
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.11.7 (2025-09-08)
 _/ |\__'_|_|_|\__'_|  |
|__/                   |

julia> using PythonCall

julia> sg=pyimport("sage.all")
ERROR: Python: TypeError: signal handler must be signal.SIG_IGN, signal.SIG_DFL, or a callable object
Python stacktrace:
 [1] signal
   @ signal ~/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/signal.py:58
 [2] cysignals.pysignals.setsignal
   @ cysignals/pysignals.pyx:319
 [3] cysignals.pysignals.changesignal.__exit__
   @ cysignals/pysignals.pyx:373
 [4] init cysignals.pysignals
   @ cysignals/pysignals.pyx:488
 [5] init sage.interfaces.process (build/cythonized/sage/interfaces/process.c:7112)
   @ sage/interfaces/process.pyx:24
 [6] <module>
   @ ~/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/site-packages/sage/parallel/use_fork.py:22
 [7] <module>
   @ ~/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/site-packages/sage/dynamics/arithmetic_dynamics/endPN_automorphism_group.py:33
 [8] <module>
   @ ~/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/site-packages/sage/dynamics/arithmetic_dynamics/projective_ds.py:66
 [9] <module>
   @ ~/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/site-packages/sage/dynamics/arithmetic_dynamics/all.py:5
 [10] <module>
   @ ~/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/site-packages/sage/dynamics/all.py:25
 [11] <module>
   @ ~/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/site-packages/sage/all.py:127
Stacktrace:
 [1] pythrow()
   @ PythonCall.Core ~/.julia/packages/PythonCall/mkWc2/src/Core/err.jl:77
 [2] errcheck
   @ ~/.julia/packages/PythonCall/mkWc2/src/Core/err.jl:10 [inlined]
 [3] pyimport(m::String)
   @ PythonCall.Core ~/.julia/packages/PythonCall/mkWc2/src/Core/builtins.jl:1458
 [4] top-level scope
   @ REPL[2]:1

julia> sg=pyimport("sage.all")
Python: <module 'sage.all' from '/home/greg/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.12/site-packages/sage/all.py'>

julia> sg.factor(sg.ZZ(376655555555555555554444444444443332346777712))
Python: 2^4 * 53 * 163 * 12391 * 219914853701821004027468433435262943

julia> sg.log(2.3)
Python: 0.832909122935104

Kali Linux on WSL PythonCall v0.9.28 CondaPkg v0.2.33 Python version: Python: '3.12.11 | packaged by conda-forge | (main, Jun 4 2025, 15:10:57) [GCC 13.3.0]' sagelib v10.7

I wonder what happens here since in pure Python that works.

[cjdoris]

This is a very mysterious error. It's to do with signal handlers - and getting Python and Julia to co-operate on signal handling is hard. I don't really know where to start with this. You could try starting julia with --handle-signals=no and see if that changes anything.

Or you can try debugging it by finding out what the incorrect value that was passed to signal was and where it came from.

Or you can just not use sage.all and just import the bits you need and hope it doesn't interact with the signal handling bits of sage.