bug#30229: Python modules installed by pip in virtualenv can't find shared objects.

[ludo@gnu.org (Ludovic Courtès)]

Hi,

Fis Trivial <ybbs.daans@hotmail.com> skribis:

> In my case, it's lightgbm (installed by pip), needs libgomp.so from gcc:lib for
> openmp support. Here is the backtrace:
>
> Traceback (most recent call last):
>   File "ex1.py", line 5, in <module>
>     import lightgbm as lgb
>   File "/home/fis/Workspace/tianchi/medical_treatment/lib/python3.5/site-packages/lightgbm/__init__.py", line 8, in <module>
>     from .basic import Booster, Dataset
>   File "/home/fis/Workspace/tianchi/medical_treatment/lib/python3.5/site-packages/lightgbm/basic.py", line 32, in <module>
>     _LIB = _load_lib()
>   File "/home/fis/Workspace/tianchi/medical_treatment/lib/python3.5/site-packages/lightgbm/basic.py", line 27, in _load_lib
>     lib = ctypes.cdll.LoadLibrary(lib_path[0])
>   File "/gnu/store/jb3n0bsdpkhvyb8y70jyr8fcx8fqssr9-python-3.5.3/lib/python3.5/ctypes/__init__.py", line 425, in LoadLibrary
>     return self._dlltype(name)
>   File "/gnu/store/jb3n0bsdpkhvyb8y70jyr8fcx8fqssr9-python-3.5.3/lib/python3.5/ctypes/__init__.py", line 347, in __init__
>     self._handle = _dlopen(self._name, mode)
> OSError: libgomp.so.1: cannot open shared object file: No such file or directory

I’d suggest hard-coding the absolute file name of libgomp.so.1 in
lightgbm/basic.py.

This is what we do, for instance, for Guile packages that use the
foreign function interface (FFI) and dynamically load shared libraries
(see ‘guile-gdbm-ffi’ as an example.)

HTH,
Ludo’.