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Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/13517 Differential Revision: D12914271 Pulled By: goldsborough fbshipit-source-id: df64fca6652525bc814f6fd3e486c87bff29b5b5
35 lines
1.4 KiB
ReStructuredText
35 lines
1.4 KiB
ReStructuredText
FAQ
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---
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Listed below are a number of common issues users face with the various parts of
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the C++ API.
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C++ Extensions
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==============
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Undefined symbol errors from PyTorch/ATen
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*****************************************
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**Problem**: You import your extension and get an ``ImportError`` stating that
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some C++ symbol from PyTorch or ATen is undefined. For example::
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>>> import extension
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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ImportError: /home/user/.pyenv/versions/3.7.1/lib/python3.7/site-packages/extension.cpython-37m-x86_64-linux-gnu.so: undefined symbol: _ZN2at19UndefinedTensorImpl10_singletonE
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**Fix**: The fix is to ``import torch`` before you import your extension. This will make
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the symbols from the PyTorch dynamic (shared) library that your extension
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depends on available, allowing them to be resolved once you import your extension.
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I created a tensor using a function from ``at::`` and get errors
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****************************************************************
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**Problem**: You created a tensor using e.g. ``at::ones`` or ``at::randn`` or
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any other tensor factory from the ``at::`` namespace and are getting errors.
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**Fix**: Replace ``at::`` with ``torch::`` for factory function calls. You
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should never use factory functions from the ``at::`` namespace, as they will
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create tensors. The corresponding ``torch::`` functions will create variables,
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and you should only ever deal with variables in your code.
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