GCC version 8 not found after package install

[LouisTrigg]

I installed the package with pip (version 10.0.1) to my Python lib (version 3.6.3) on macOS Sierra (version 10.12.6), along with the dependencies found in the documentation, including open-mpi, cmake and gcc.

However, I kept receiving the following exception when I try to import the package using Jupyter notebook (version 5.0.0):

OSError: dlopen(/Users/admin/anaconda3/lib/python3.6/site-packages/lightgbm/lib_lightgbm.so, 6): Library not loaded: /usr/local/opt/gcc/lib/gcc/7/libgomp.1.dylib
Referenced from: /Users/admin/anaconda3/lib/python3.6/site-packages/lightgbm/lib_lightgbm.so
Reason: image not found

brew install gcc installed version 9, and somehow only version 8 is in the /usr/local/opt/gcc/lib/gcc folder, but the filepath above shows the package is still searching for version 7, so I kept receiving the error until I specifically downloaded version 7 and manually inserted it in the /usr/local/opt/gcc/lib/gcc/ folder.

I'm confused about whether this an issue with the filepath or homebrew?

Steps to reproduce (corrected)

1. Brew install open-mpi, cmake, gcc
2. git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
   export CXX=g++-9 CC=gcc-9 # replace 7 with version of gcc installed on your machine
   mkdir build ; cd build
   cmake ..
   make -j4
3. pip install lightgbm

[StrikerRUS]

There is no gcc-9 yet. You should use this command export CXX=g++-8 CC=gcc-8.
Same as #1369.

[StrikerRUS]

Also your order of steps is incorrect. Firstly, build LightGBM library with this guide. Only after successful compilation you need to install Python-package:

cd LightGBM/python-package
python setup.py install --precompile

[LouisTrigg]

Thanks. I may have been using gcc --version incorrectly to check the version from homebrew.

[LouisTrigg]

I'm reopening this issue after originally closing it by thinking the problem was incorrectly assuming a version 9 for gcc in the line export CXX=g++-9 CC=gcc-9.

I double-checked everything by uninstalling and reinstalling via the following steps:

pip uninstall lightgbm

brew reinstall open-mpi 
brew reinstall cmake
brew reinstall gcc (resulting in version 8.1.0)

git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
export CXX=g++-8 CC=gcc-8
mkdir build ; cd build
cmake ..
make -j4

pip install lightgbm

However, I still received the same error when I imported the package into the notebook:

OSError: dlopen(/Users/admin/anaconda3/lib/python3.6/site-packages/lightgbm/lib_lightgbm.so, 6): Library not loaded: /usr/local/opt/gcc/lib/gcc/7/libgomp.1.dylib
Referenced from: /Users/admin/anaconda3/lib/python3.6/site-packages/lightgbm/lib_lightgbm.so
Reason: image not found

[StrikerRUS]

You are doing everything right now , except one last step.

As I said before, you need run

cd LightGBM/python-package
python setup.py install --precompile

instead of

pip install lightgbm

Installing from pip you are getting precompiled version of the LightGBM library, which comes inside the wheel from the PyPI site and requires gcc-7 (@guolinke BTW, maybe it's time to update the version?). So, all your previous steps aimed to compile the library file are just ignored.

Of course, you can manually replace the library file into the Python-package in this folder /Users/admin/anaconda3/lib/python3.6/site-packages/lightgbm with one which you've just compiled. But agree that python setup.py install --precompile is much easier 😃 .

[guolinke]

@StrikerRUS yeah, we can update the version.

[LouisTrigg]

@StrikerRUS It worked. You're right - compiling the library file is much more streamlined than the alternative. Thanks!