C++ static linking of ONNX results in conflicts with existing symbols

We are trying to implement an ONNX importer for a C++ runtime. Our runtime will be used by frontend applications, which also use ONNX models.

When trying to execute a process which runs both frontend and backend components, we are seeing errors indicating that a Protocol Buffers symbol name conflicts with the existing symbol.

[libprotobuf ERROR google/protobuf/descriptor_database.cc:109] Symbol name "onnx.AttributeProto" conflicts with the existing symbol "onnx.AttributeProto".
[libprotobuf FATAL google/protobuf/descriptor.cc:1164] CHECK failed: generated_database_->Add(encoded_file_descriptor, size):
terminate called after throwing an instance of 'google::protobuf::FatalException'
 what():  CHECK failed: generated_database_->Add(encoded_file_descriptor, size):
Aborted (core dumped)

Did anyone already run into this problem? Have you found a good solution to this issue?

[apwojcik]

I would like to let you know that we eventually fixed the problem by statically linking the protobuf library into our shared object. No namespace change was required in ONNX and the client application is working fine with our library.

[yinghai]

This will likely have problems as protobuf has a global registry based on proto file name. If you have two .so file that contains onnx.pb.cc, this issue will happen. The trick we do is to define a different namespace for onnx when used in third-party and rely on onnx’s CMakefile to do the symbol replacement and renaming. Here is an example:

https://github.com/onnx/onnx-tensorrt/blob/fa0964e8477fc004ee2f49ee77ffce0bf7f711a9/CMakeLists.txt#L93-L97