✨ support local cache for models

[prashantgupta24]

Updates how files are pulled from HF Hub to support offline usage with cached files and a fallback in case of networking issues or if HF Hub is down.

(Without this change, you have to pass the explicit path to the model in your local HF cache as the model name.)

Taken bits from #3125

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[simon-mo]

This looks pretty reasonable to me. Another place we use snapshot_download is when loading the tokenizer and other config. It would be useful to search for snapshot download or .from_pretrained call.

Any suggestion on how to test this?

[prashantgupta24]

What I can do is create another function that does snapshot_download 2 times, one with local_files false, if that fails, try with local_files True. Then both download_weights_from_hf and get_quant_config can use that function to avoid duplication of code. I will remove the existing try catch from loader.py.

For the tokenizer, it uses modelscope.hub.snapshot_download, I will see if that has the same functionality as HF's snapshot_download for local_files mode.

[prashantgupta24]

Or better yet, I can do this

 hf_folder = snapshot_download(
            model_name_or_path,
            allow_patterns=allow_patterns,
            cache_dir=cache_dir,
            tqdm_class=DisabledTqdm,
            revision=revision,
            local_files_only=HF_HUB_OFFLINE,
        )

?
That way, a network connection attempt is made ONLY if HF_HUB_OFFLINE is unset.

[njhill]

Thanks @prashantgupta24 (and to @tjohnson31415 for the original PR).

Not sure whether you tested this, but in theory the local_files_only=HF_HUB_OFFLINE shouldn't be necessary with HF's snapshot_download since it already honors this env var.

But it also doesn't harm I guess, and looks like it might still need to be passed like this to modelscope's snapshot_download.

There's another instance of that in loader.py which should be similarly updated I think?

[prashantgupta24]

@njhill whoops forgot that one, updated it, thanks!

And yeah I added HF_HUB_OFFLINE to make it consistent across both.

[prashantgupta24]

Will add a test case for this tomorrow!

[rkooo567]

I think we should test it? why don't we download the model -> remove instance -> restart the instance with a local file?

[prashantgupta24]

I think we should test it? why don't we download the model -> remove instance -> restart the instance with a local file?

Yes I am planning to add that

[njhill]

Thanks @prashantgupta24 and @tjohnson31415!

[saivarunk]

Is there any documentation on how to use the offline option for downloading Huggingface model?

@njhill @prashantgupta24 @tjohnson31415

[prashantgupta24]

@saivarunk if offline mode is enabled, no networking calls are made and models are not downloaded from HF, instead vllm will try to look for that model in the local cache.

[rkooo567]

@prashantgupta24 maybe we can update this to the doc (model section) https://docs.vllm.ai/en/latest/?