Python: getting core dumped on import

[stefanmaak]

What version of OR-Tools and what language are you using?
Version: 9.12
Language: Python3.12.3

Which solver are you using (e.g. CP-SAT, Routing Solver, GLOP, BOP, Gurobi)
I try to use the CP solver (I fail importing from SAT)

What operating system (Linux, Windows, ...) and version?
Linux (Ubuntu)

What did you do?
Steps to reproduce the behavior:
I get a core dump while importing ortools modules in a specific context ,i.e., after doing other imports.
I broke it down to the following minimal example:

1. create a python environment (i am using python3 -m venv) with only gpcio-tools and ortools installed:

Package         Version
--------------- -----------
absl-py         2.2.2
grpcio          1.71.0
grpcio-tools    1.71.0
immutabledict   4.2.1
numpy           2.2.4
ortools         9.12.4544
pandas          2.2.3
pip             24.0
protobuf        5.29.4
python-dateutil 2.9.0.post0
pytz            2025.2
setuptools      78.1.0
six             1.17.0
tzdata          2025.2

2. run this python script:

import grpc_tools.protoc
# uncommenting the following line causes bad_alloc instead of invalid pointer
import ortools
print("importing ortools.sat.python.cp_model")
import ortools.sat.python.cp_model
print("Finished importing all modules.")

What did you expect to see
A successful import.

What did you see instead?

importing ortools.sat.python.cp_model
munmap_chunk(): invalid pointer
Aborted (core dumped)

Make sure you include information that can help us debug (full error message, model Proto).

Anything else we should know about your project / environment
I created this example by listing all loaded modules in python before the critical import happened. Then I deleted them sequentially without the error disappearing. In the real project the import of grpc-related modules happens because is use sila2 (is on pip).

[lperron]

Most likely a protobuf conflict. Could be abseil too.
What are the deps of grpcio ?

[stefanmaak]

I do not know. But there are no dependency conflicts in the test environment.
I get: grpcio-tools 1.71.0 requires protobuf<6.0dev,>=5.26.1

[Mizux]

did you try to import ortools first ? order can matter since all c++ symbols are loaded in the same process context (first loaded, subsequent symbols load are ignored)

[stefanmaak]

I just tried it:

import ortools
import ortools.sat.python.cp_model
import grpc_tools.protoc

This changes the error output to

WARNING: All log messages before absl::InitializeLog() is called are written to STDERR
E0000 00:00:1747303586.576435  235599 descriptor_database.cc:622] Invalid package name: google.protobuf0��b�G
corrupted size vs. prev_size
Aborted (core dumped)

However, in my actual project I have to load the grpc stuff first and in general, a wrong import order in python should not cause such erros, right? I am no expert on c or c++.

ps: I am currently using ortools 9.9 which avoids avoids those core dumps, but 9.12 is the clearly superior solver.

[Mizux]

seems likely an ODR violation by grpcio using a static lib for protobuf instead of building a shared lib of it....

see: protocolbuffers/protobuf#17465

[stefanmaak]

So, nothing to do here and I should close my issue and hope the grcpio developers finally fix that? I see you opened the issue there 10 month ago. Unfortunately, I do not really understand the details.

[Mizux]

I need to dig to fully understand and reproduce your error but maybe by building from source grpcio with protobuf as a "module" see https://github.com/grpc/grpc/blob/828b2679ea647472c0ddad9a11140f121120b73a/cmake/protobuf.cmake#L15
may be the solution to your compatibility issue...

First I should take a look at the symbols in the grpcio-tools wheel package...