ImportError: Could not import _ext module.

Hi, team Thanks for sharing the wonderful project! I miss this bug:

Traceback (most recent call last):
  File "/disk/tia/votenet_v0/pointnet2/pointnet2_utils.py", line 26, in <module>
    import pointnet2._ext as _ext
ImportError: /home/ubuntu/.conda/envs/tia37/lib/python3.7/site-packages/pointnet2-0.0.0-py3.7-linux-x86_64.egg/pointnet2/_ext.cpython-37m-x86_64-linux-gnu.so: undefined symbol: _ZN6caffe26detail37_typeMetaDataInstance_preallocated_32E

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "train.py", line 159, in <module>
    MODEL = importlib.import_module(FLAGS.model)  # import network module
  File "/home/ubuntu/.conda/envs/tia37/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/disk/tia/votenet_v0/models/votenet.py", line 19, in <module>
    from backbone_module import Pointnet2Backbone
  File "/disk/tia/votenet_v0/models/backbone_module.py", line 19, in <module>
    from pointnet2_modules import PointnetSAModuleVotes, PointnetFPModule
  File "/disk/tia/votenet_v0/pointnet2/pointnet2_modules.py", line 21, in <module>
    import pointnet2_utils
  File "/disk/tia/votenet_v0/pointnet2/pointnet2_utils.py", line 30, in <module>
    "Could not import _ext module.\n"
ImportError: Could not import _ext module.
Please see the setup instructions in the README: https://github.com/erikwijmans/Pointnet2_PyTorch/blob/master/README.rst

It seems that something goes wrong during the pointnet2 compile. I use python 3.7, pytorch 1.4.0, cuda 10.0, gcc 7.5.0 Could you please help me to compile with this?

[sujeongcha]

This worked for me.

1. Install the latest version of Pointnet2_Pytorch pip install "git+git://github.com/erikwijmans/Pointnet2_PyTorch.git#egg=pointnet2_ops&subdirectory=pointnet2_ops_lib"
2. Change pointnet2_utils.py line 26 to: import pointnet2_ops._ext as _ext

[IliasMAOUDJ]

Downgrading to Pytorch 1.1 and using python 3.6 worked for me.