cppyy unable to open shared library

Question

I am trying to load a .so in cppyy, but getting below error.

Is there any way to see what exact error is there, due to which Load() is failing

load_my_lib.py:57: in <module>
    cppyy.load_library("mylib.so")
.venv/lib/python3.6/site-packages/cppyy/__init__.py:219: in load_library
    sc = gSystem.Load(name)
E   cppyy.gbl.std.exception: int CppyyLegacy::TSystem::Load(const char* module, const char* entry = "", CppyyLegacy::Bool_t system = kFALSE) =>
E       exception: std::exception

Answer 1

It looks like the loading of the library results in a std::exception being thrown that has an empty result out of it's what().

Both the use of std::exception rather than one of its derived classes, as well as having no message returned from what() are a bit of an uncommon use, and I'm not aware of anything in the load library call itself that can cause that. Thus, my best guess would be that it gets thrown during the creation of a global or static variable that lives in mylib.so.

Do you know whether there are any static or global variables in that library? These may also live in a library that mylib.so is linked with, and which gets pulled in when loading.

Another way that sometimes gets a better diagnostic (although I doubt it in this case, as it doesn't handle C++ exceptions) is to load the library with ctypes instead:

import ctypes
d = ctypes.CDLL("mylib.so", ctypes.RTLD_GLOBAL)

(ctypes.CDLL does not have portable behavior, which is why load_library exists, but on most, not all, Linux distros it's a perfectly fine alternative.)