CoolProp fails to import when cadquery is imported first

[mariap-pf]

When importing cadquery before CoolProp, the script silently hangs and does not proceed to execution. Reversing the import order resolves the issue. Does anyone have an idea of what could be the problem?

To Reproduce

import cadquery
import CoolProp

if __name__ == "__main__":
    print("hello world")

Environment

OS: Ubuntu 22.04
Python version: 3.10
cadquery version: https://github.com/CadQuery/cadquery/tree/2698db5c395705eb36e42bb5d4ab5944daf24436
CoolProp version: 6.6.0
Was CadQuery installed using Conda?: no, it was installed using pip
Using: Python interpreter

[adam-urbanczyk]

Coolprop is not related in any way to CQ so that is rather esoteric (guess: ABI issue, but I wouldn't know how/why). Would you be able to:

a) check with conda-forge built packages (just download micromamba and do not bother with setting up your shell)
b) attach gdb and provide a backtrace bt

[lorenzncode]

I can reproduce the hang without cadquery. I'll append to CoolProp/CoolProp#2512

[eguiraud-pf]

Added some more details and a proposed fix at CoolProp/CoolProp#2512 (comment) (namely, using latest master for the C++ rapidjson version in coolprop).

By sheer luck the C++ rapidjson version that cadquery's wheels use seems to be compatible with the latest C++ rapidjson commit, even if the cadquery-ocp build system does not really pick a version: if I understand correctly, it just looks for rapidjson in the system.

@adam-urbanczyk I would recommend to patch cadquery-ocp's build system so that it fetches the latest version of C++ rapidjson rather than picking it up from the system.

[adam-urbanczyk]

I'm not maintaining the ocp-build-system repo and I in general recommend to use the conda-forge package (which most likely would save you form the issue because in that ecosystem rapidjson is an explicit dep of both occt and coolprop). AFAICT ocp_build-system fetches the rapidjson via conda. This happens to be 1.1.0.post20240409. This could be made explicit in the env file.

[eguiraud-pf]

I don't think we are in the position to switch from pip to conda any time soon at Proxima, but point taken that this is likely a non-issue in the conda world.

[adam-urbanczyk]

Fair enough. As discussed in CoolProp/CoolProp#2512 adjusting the symbol visibility in cadquery-ocp is also an option here (probably a local optimum given your constraints).