[Cherry-pick 2.0.1] Fix virtual function issue with CTC decoder (#3230) #3238
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Summary: Currently, creating CTCDecoder object by passing a language model to `lm` argument without assigning it to a variable elsewhere causes `RuntimeError: Tried to call pure virtual function "LM::start"`. According to discussions on PyBind11, ( pybind/pybind11#4013 and pybind/pybind11#2839 ) this is due to Python object garbage-collected by the time it's used by code implemented in C++. It attempts to call methods defined in Python, which overrides the base pure virtual function, but the object which provides this override gets deleted by garbage collrector, as the original object is not reference counted. This commit fixes this by simply assiging the given `lm` object as an attribute of CTCDecoder class. Address #3218 Pull Request resolved: #3230 Reviewed By: hwangjeff Differential Revision: D44642989 Pulled By: mthrok fbshipit-source-id: a90af828c7c576bc0eb505164327365ebaadc471
mthrok
changed the title
nateanl
approved these changes
Apr 5, 2023
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Summary:
Currently, creating CTCDecoder object by passing a language model to
lmargument without assigning it to a variable elsewhere causesRuntimeError: Tried to call pure virtual function "LM::start".According to discussions on PyBind11, (
pybind/pybind11#4013 and pybind/pybind11#2839
) this is due to Python object garbage-collected by the time it's used by code implemented in C++. It attempts to call methods defined in Python, which overrides the base pure virtual function, but the object which provides this override gets deleted by garbage collrector, as the original object is not reference counted.
This commit fixes this by simply assiging the given
lmobject as an attribute of CTCDecoder class.Address #3218
Pull Request resolved: #3230
Reviewed By: hwangjeff
Differential Revision: D44642989
Pulled By: mthrok
fbshipit-source-id: a90af828c7c576bc0eb505164327365ebaadc471