Stuck at " Loading segmented_maxsim_cpp extension (set COLBERT_LOAD_TORCH_EXTENSION_VERBOSE=True for more info)..."

I'm running on a CPU-only host.

My pip freeze output:
aiohttp==3.9.5
aiosignal==1.3.1
annotated-types==0.6.0
anyio==4.3.0
async-timeout==4.0.3
attrs==23.2.0
beautifulsoup4==4.12.3
bitarray==2.9.2
blinker==1.8.2
catalogue==2.0.10
certifi==2024.2.2
charset-normalizer==3.3.2
click==8.1.7
colbert-ai==0.2.19
dataclasses-json==0.6.6
datasets==2.19.1
Deprecated==1.2.14
dill==0.3.8
dirtyjson==1.0.8
distro==1.9.0
exceptiongroup==1.2.1
faiss-cpu==1.8.0
fast-pytorch-kmeans==0.2.0.1
filelock==3.14.0
Flask==3.0.3
frozenlist==1.4.1
fsspec==2024.3.1
git-python==1.0.3
gitdb==4.0.11
GitPython==3.1.43
greenlet==3.0.3
h11==0.14.0
httpcore==1.0.5
httpx==0.27.0
huggingface-hub==0.23.0
idna==3.7
itsdangerous==2.2.0
Jinja2==3.1.4
joblib==1.4.2
jsonpatch==1.33
jsonpointer==2.4
langchain==0.1.19
langchain-community==0.0.38
langchain-core==0.1.52
langchain-text-splitters==0.0.1
langsmith==0.1.56
llama-index==0.10.36
llama-index-agent-openai==0.2.4
llama-index-cli==0.1.12
llama-index-core==0.10.36
llama-index-embeddings-openai==0.1.9
llama-index-indices-managed-llama-cloud==0.1.6
llama-index-legacy==0.9.48
llama-index-llms-openai==0.1.18
llama-index-multi-modal-llms-openai==0.1.5
llama-index-program-openai==0.1.6
llama-index-question-gen-openai==0.1.3
llama-index-readers-file==0.1.22
llama-index-readers-llama-parse==0.1.4
llama-parse==0.4.2
llamaindex-py-client==0.1.19
MarkupSafe==2.1.5
marshmallow==3.21.2
mpmath==1.3.0
multidict==6.0.5
multiprocess==0.70.16
mypy-extensions==1.0.0
nest-asyncio==1.6.0
networkx==3.3
ninja==1.11.1.1
nltk==3.8.1
numpy==1.26.4
onnx==1.16.0
openai==1.28.0
orjson==3.10.3
packaging==23.2
pandas==2.2.2
pillow==10.3.0
protobuf==5.26.1
pyarrow==16.0.0
pyarrow-hotfix==0.6
pydantic==2.7.1
pydantic_core==2.18.2
pynvml==11.5.0
pypdf==4.2.0
python-dateutil==2.9.0.post0
python-dotenv==1.0.1
pytz==2024.1
PyYAML==6.0.1
RAGatouille==0.0.8.post2
regex==2024.5.10
requests==2.31.0
safetensors==0.4.3
scikit-learn==1.4.2
scipy==1.13.0
sentence-transformers==2.7.0
six==1.16.0
smmap==5.0.1
sniffio==1.3.1
soupsieve==2.5
SQLAlchemy==2.0.30
srsly==2.4.8
striprtf==0.0.26
sympy==1.12
tenacity==8.3.0
threadpoolctl==3.5.0
tiktoken==0.6.0
tokenizers==0.19.1
torch==2.2.0+cpu
tqdm==4.66.4
transformers==4.40.2
typing-inspect==0.9.0
typing_extensions==4.11.0
tzdata==2024.1
ujson==5.9.0
urllib3==2.2.1
voyager==2.0.6
Werkzeug==3.0.3
wrapt==1.16.0
xxhash==3.4.1
yarl==1.9.4

The code in question is :
def create_or_get_colbert_model(username):
index_name=username+"_report_history"
index_path = **PATH**/.ragatouille/colbert/indexes/"+index_name+"/"
print("Index path = ",index_path)
if os.path.exists(index_path):
RAG = RAGPretrainedModel.from_index(index_path)
else:
RAG = RAGPretrainedModel.from_pretrained("colbert-ir/colbertv2.0")
return RAG


After printing "Index path = " , index_path, I get :
Loading segmented_maxsim_cpp extension (set COLBERT_LOAD_TORCH_EXTENSION_VERBOSE=True for more info)...

This happens even after creating a fresh ENV, and fresh installs of torch-cpu-2.2.0, sentence_transformers, transformers and ragatouille.

Start by reproducing the CPU-only case around create_or_get_colbert_model and the RAGPretrainedModel.from_index/from_pretrained calls. Read the loading path that emits “Loading segmented_maxsim_cpp extension” and use COLBERT_LOAD_TORCH_EXTENSION_VERBOSE for more information. Done means the reported CPU environment no longer remains stuck at extension loading, with the relevant behavior verified.

Written by the indexing model from the issue text.