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PyctcDecode fails when running spawn context (multiprocessing)

See original GitHub issue

I have opened a Transformers PR, yet the PR failed due to changing context from fork to spawn in

from multiprocessing import get_context
.
.
.
pool = get_context("spawn").Pool(num_processes)

in the following file src/transformers/models/wav2vec2_with_lm/processing_wav2vec2_with_lm.py

My question is “How to run pyctcdecode batch decode on WindowsOS?” Is there any way I can help? or contribute to fix that issue?

Issue Analytics

State:
Created a year ago
Reactions:1
Comments:5

Top GitHub Comments

1reaction

lopez86commented, May 25, 2022

I’ve added some code that will allow for either not using multiprocessing or if a spawn context pool is found will bypass multiprocessing as well. It’s not a true solution but it should unblock things at least. If anyone has some way to enable actually using the pool with a spawn context without hurting performance, please discuss or consider making a PR

1reaction

lopez86commented, May 23, 2022

I was looking into this a bit, and what’s happening is that because the language model is included as a class variable, fork works without having to reload the language model, but spawn ends up creating processes where the language model is missing. If the language model is instead made an instance variable, both fork and spawn, but each process needs to reload the language model, which will likely wipe out any performance improvements from using multiprocessing. I’m not sure what a good solution to this would be

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