Trying to link mip to Debian's CBC package throws undefined error

I installed coinor-cbc to my armhf system, and did this:

export PMIP_CBC_LIBRARY="/usr/lib/arm-linux-gnueabihf/libCbcSolver.so.3.9.9"
export LD_LIBRARY_PATH="/usr/lib/arm-linux-gnueabihf/"

as established here.

Then, when I try to execute it on Python’s console, I do:

>>> from mip import Model, MAXIMIZE, CBC, INTEGER, OptimizationStatus
>>> model = Model(sense=MAXIMIZE, solver_name=CBC)

And I inmediately get the error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.7/dist-packages/mip/model.py", line 93, in __init__
    import mip.cbc
  File "/usr/local/lib/python3.7/dist-packages/mip/cbc.py", line 600, in <module>
    Osi_getNumCols = cbclib.Osi_getNumCols
  File "/usr/local/lib/python3.7/dist-packages/cffi/api.py", line 912, in __getattr__
    make_accessor(name)
  File "/usr/local/lib/python3.7/dist-packages/cffi/api.py", line 908, in make_accessor
    accessors[name](name)
  File "/usr/local/lib/python3.7/dist-packages/cffi/api.py", line 838, in accessor_function
    value = backendlib.load_function(BType, name)
AttributeError: function/symbol 'Osi_getNumCols' not found in library '/usr/lib/arm-linux-gnueabihf/libCbcSolver.so.3.9.9': /usr/lib/arm-linux-gnueabihf/libCbcSolver.so.3.9.9: undefined symbol: Osi_getNumCols

I am using

• Python 3.7.3
• mip 1.12.0
• coinor-cbc 2.9.9+repack1-1
• Debian GNU/Linux 10 (buster)
• Kernel: Linux 4.14.78-g8e54a4b
• Architecture: armv7l

[tkralphs]

Sorry, I misspoke. I didn’t mean to say dynamic linking, I meant symbolic linking. You created a symbolic link from libCbc to libCbcSolver when I think you could just directly point python-mip to libCbc by setting PMIP_CBC_LIBRARY.

[tkralphs]

I tried this today and it worked, however it seems that the library has been renamed in the Cbc master and Python-MIP has not been updated (yet).

Yes, there used to be a libCbc and a libCbcSolver, but this separation did not serve much purpose, so the libraries were merged as part of the on-going refactoring being undertaken in the master branch. I’m not sure why you need to do the dynamic linking , though. You should be able to just set PMIP_CBC_LIBRARY to point directly to libCbc, unless I’m missing something.

We are still trying to get to a formal release of the code in Cbc master branch, but it still needs some work and developer bandwidth is severely limited. The work to be done doesn’t need that much knowledge of Cbc internals, volunteers are welcome. See coin-or/Cbc/discussions/465.