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Issue when exporting SwinForImageClassification to ONNX format

See original GitHub issue

System Info

1. Libraries version

transformers == 4.23.1 / torch == 1.12.1 / onnx = 1.12.0

2. Context

I trained an Image Classifier using SwinForImageClassification with a custom number of labels. I want to put it in production using the ONNX format. So I need to export my model in this format.


I used the python -m transformers.onnx [...] as recommended in your documentation. Without considering some warning (available hereabove) during the ONNX creation, the model’s creation works. However the test that compares values (validate_model_outputs) at the end fails:

$ python -m transformers.onnx --model='test_onnx/swin_classif/sources' test_onnx/swin_classif/ --feature='image-classification' --preprocessor=feature_extractor
Validating ONNX model...
	-[✓] ONNX model output names match reference model ({'logits'})
	- Validating ONNX Model output "logits":
		-[✓] (3, 160) matches (3, 160)
		-[x] values not close enough (atol: 0.0001)

I tried to use torch.onnx.export and transformers.onnx.export. The same behaviour happened. BUT when I tried with the model ViT (ViTForImageClassification), everything worked well !!

3. How to reproduce the issue

In the dedicated section.

I don’t know if I miss something obvious here ? Thank you for your work 🤗 and I hope we can solve this ! 🚀

4. Warning during ONNX creation

here is the different warning I have when creating the ONNX model: (Each happen multiple times for different operation)

- TracerWarning: Converting a tensor to a Python boolean might cause the trace to be incorrect. We can't record the data flow of Python values, so this value will be treated as a constant in the future. This means that the trace might not generalize to other inputs!
- UserWarning: __floordiv__ is deprecated, and its behavior will change in a future version of pytorch. It currently rounds toward 0 (like the 'trunc' function NOT 'floor'). This results in incorrect rounding for negative values. To keep the current behavior, use torch.div(a, b, rounding_mode='trunc'), or for actual floor division, use torch.div(a, b, rounding_mode='floor').
- WARNING: The shape inference of prim::Constant type is missing, so it may result in wrong shape inference for the exported graph. Please consider adding it in symbolic function.

Who can help?

@NielsRogge, @sgugger


  • The official example scripts
  • My own modified scripts


  • An officially supported task in the examples folder (such as GLUE/SQuAD, …)
  • My own task or dataset (give details below)


Here is the code to reproduce the issue: step 1: Save pretrained

from transformers import SwinForImageClassification, AutoFeatureExtractor
pretrained_path = "microsoft/swin-tiny-patch4-window7-224"

swin_classif = SwinForImageClassification.from_pretrained(pretrained_path, ignore_mismatched_sizes=True, num_labels=160)
feat_extract = AutoFeatureExtractor.from_pretrained(pretrained_path)


step 2: Build ONNX python -m transformers.onnx --model='test_onnx/swin_classif/sources' test_onnx/swin_classif/ --feature='image-classification' --preprocessor=feature_extractor

Expected behavior

I would expect the ONNX creation for SwinForImageClassification to work: given the same input, SwinForImageClassification model produces the same output as its exported version in ONNX format.

Issue Analytics

  • State:open
  • Created a year ago
  • Comments:11 (5 by maintainers)

github_iconTop GitHub Comments

fxmartycommented, Nov 28, 2022

@BenoitLeguay I can’t reproduce the issue with python -m transformers.onnx --model microsoft/swin-base-patch4-window12-384-in22k swin-bas-onnx/ --feature image-classification. Is it always failing for you?



Could you try with these versions? Or give more details on your setup / a dockerfile to reproduce?

I notice that the ONNX export gives a lot of warnings, so it could be the exported models can not handle certain dynamic cases. It is part of to have a better user experience with exported ONNX models and the case they support / dont’ support. You can expect more work being put on the ONNX export in the Optimum lib (doc here), notably a stronger test suite for the exported models.

fxmartycommented, Nov 28, 2022

Ok great! Don’t hesitate to share if with your old laptop + transformers==4.24.0 you can reproduce the issue. Otherwise it could be that it has been fixed in this version (maybe )

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