[BUG] Appending-Runtime-LoRA-weights

[royallavanya140]

OS

Linux

GPU Library

CUDA 12.x

Python version

3.12

Pytorch version

2.3.1

Model

mistral-v0.3-instruct

Describe the bug

i hosted llm using fastapi and accept the lora weights from the users but If I receive the weights when the model is bsy in generation. is there any way to edit the weights without disturbing current generation.

Reproduction steps

• host llm with fastapi and the payload is messages and loraspath.
• give generation call parallelly at a same time with 2 diff lora paths.

Expected behavior

LoRAs cannot be updated while there are jobs in the generator queue

Logs

No response

Additional context

No response

Acknowledgements

• I have looked for similar issues before submitting this one.
• I understand that the developers have lives and my issue will be answered when possible.
• I understand the developers of this program are human, and I will ask my questions politely.

[turboderp]

Problem is that you can't batch forward passes with different LoRA settings. Applying a LoRA effectively changes the weights of the model. It's a temporary change via a low-rank overlay, but it's still effectively the same as swapping out the model for a different one. Which makes sense as long as there aren't any requests in the queue, but while requests are processing, I don't know how the framework should interpret that..?

[psych0v0yager]

@turboderp, to be clear would it be possible to append LoRA weights if you wait until there are no requests in cue? For the dynamic generator is it as simple as adding generator.set_loras(lora) when the cue is empty, or are there additional considerations in play?

As for multiple Loras in runtime, it is theoretically possible and has been done by this library (https://github.com/S-LoRA/S-LoRA), this is how vllm lets you run multiple at runtime. However, integrating into exllama seems like a massive undertaking.

[royallavanya140]

@turboderp bro, is that true!