ImportError: dynamic module does not define module export function (PyInit_libKeOpsnumpy5ac3d464a2)

[heslowen]

Hello!
There's something wrong when I run the example code as follow.
Actually I see this bug in #17, but I think they are not the same because it's ok for the first time in #17 but failed in my machine.

code

import numpy as np
import pykeops.numpy as pknp

x = np.arange(1, 10).reshape(-1, 3).astype('float32')
y = np.arange(3, 9).reshape(-1, 3).astype('float32')
my_conv = pknp.Genred('SqNorm2(x - y)', ['x = Vi(3)', 'y = Vj(3)'])
res = my_conv(x, y, backend='CPU')
assert res.shape == (2, 1)
print("okay")

nvcc --version

nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2017 NVIDIA Corporation
Built on Fri_Sep__1_21:08:03_CDT_2017
Cuda compilation tools, release 9.0, V9.0.176

cmake --version

cmake version 3.15.3

which python

/home/lowen/anaconda3/envs/lowenEnv/bin/python

python --version

Python 3.6.8 :: Anaconda, Inc.

gcc --version

gcc (GCC) 7.4.0
Copyright © 2017 Free Software Foundation, Inc.

---

output

Compiling libKeOpsnumpy5ac3d464a2 in /home/lowen/.cache/pykeops-1.1.2-cpython-36//build-libKeOpsnumpy5ac3d464a2:
       formula: Sum_Reduction(SqNorm2(x - y),1)
       aliases: x = Vi(0,3); y = Vj(1,3); 
       dtype  : float64
... Done.
Traceback (most recent call last):
  File "xjbx.py", line 972, in <module>
    test_geomloss()
  File "xjbx.py", line 936, in test_geomloss
    my_conv = pknp.Genred('SqNorm2(x - y)', ['x = Vi(3)', 'y = Vj(3)'])
  File "/home/lowen/anaconda3/envs/lowenEnv/lib/python3.6/site-packages/pykeops/numpy/generic/generic_red.py", line 114, in __init__
    self.myconv = LoadKEops(self.formula, self.aliases, self.dtype, 'numpy').import_module()
  File "/home/lowen/anaconda3/envs/lowenEnv/lib/python3.6/site-packages/pykeops/common/keops_io.py", line 52, in import_module
    return importlib.import_module(self.dll_name)
  File "/home/lowen/anaconda3/envs/lowenEnv/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 658, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 571, in module_from_spec
  File "<frozen importlib._bootstrap_external>", line 922, in create_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
ImportError: dynamic module does not define module export function (PyInit_libKeOpsnumpy5ac3d464a2)

[heslowen]

I create a new conda virtual environment and install all the demand packages(python,numpy,cmake,pytorch,gcc,cuda), but it failed again...I got the same output as mentioned above.
Someone pleases help me! T_T

[joanglaunes]

I think the problem is that your gcc and nvcc versions are not compatible. You need to upgrade cuda toolkit or downgrade gcc. To check, you can try this : download GetGpuProps.cu which is in keops/keops/examples and try to compile via
nvcc GetGpuProps.cu
My guess is that it will output "gcc >6 is not supported".

[heslowen]

Yes, you are right. When i compile GetGpuProps.cu, it output:

error -- unsupported GNU version! gcc versions later than 6 are not supported!
 error -- unsupported GNU version! gcc versions later than 6 are not supported!

but, when I compile it in a new conda virtual environment(gcc7.3,cudatoolkit10.0.130), it output

nvcc GetGpuProps.cu 
nvcc fatal   : Path to libdevice library not specified

[joanglaunes]

Ok, but it is still a problem with your installation of cuda ; it is not a KeOps issue. The only solution I can give is to upgrade Cuda to version 10 as root, not via the anaconda package.

[heslowen]

Yes, thanks for your help! Hope that after I upgrade Cuda everything is ok~