[PR #24338] fix: prevent STT from blocking the uvicorn event loop #66463

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GiteaMirror · 2026-05-06T12:50:24-05:00

GiteaMirror commented

2026-05-06 12:50:24 -05:00

📋 Pull Request Information

Original PR: https://github.com/open-webui/open-webui/pull/24338
Author: @Classic298
Created: 5/3/2026
Status: 🔄 Open

Base: dev ← Head: fix/stt-blocking-event-loop

📝 Commits (1)

eec14f1 fix: prevent STT from blocking the uvicorn event loop

📊 Changes

1 file changed (+3 additions, -2 deletions)

View changed files

📝 backend/open_webui/routers/audio.py (+3 -2)

📄 Description

@tjbck urgent fix for upcoming version

This was tested and confirmed working in #24196 comments

The transcription endpoint was async but called the synchronous transcribe() function directly, blocking the single-threaded uvicorn event loop for the entire duration of inference. This caused all HTTP and WebSocket connections to stall for every user on the instance during STT processing.

Add asyncio import
Use async UploadFile.read() instead of synchronous file.file.read()
Offload the blocking transcribe() call via asyncio.to_thread()

Closes #24169

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_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/open-webui/open-webui/pull/24338 **Author:** [@Classic298](https://github.com/Classic298) **Created:** 5/3/2026 **Status:** 🔄 Open **Base:** `dev` ← **Head:** `fix/stt-blocking-event-loop` --- ### 📝 Commits (1) - [`eec14f1`](https://github.com/open-webui/open-webui/commit/eec14f1c00401b84ff461653dae975aef7240166) fix: prevent STT from blocking the uvicorn event loop ### 📊 Changes **1 file changed** (+3 additions, -2 deletions) <details> <summary>View changed files</summary> 📝 `backend/open_webui/routers/audio.py` (+3 -2) </details> ### 📄 Description @tjbck urgent fix for upcoming version This was tested and confirmed working in #24196 comments The transcription endpoint was async but called the synchronous transcribe() function directly, blocking the single-threaded uvicorn event loop for the entire duration of inference. This caused all HTTP and WebSocket connections to stall for every user on the instance during STT processing. - Add asyncio import - Use async UploadFile.read() instead of synchronous file.file.read() - Offload the blocking transcribe() call via asyncio.to_thread() Closes #24169 ### Contributor License Agreement  - [X] By submitting this pull request, I confirm that I have read and fully agree to the [Contributor License Agreement (CLA)](https://github.com/open-webui/open-webui/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT), and I am providing my contributions under its terms. > [!NOTE] > Deleting the CLA section will lead to immediate closure of your PR and it will not be merged in. --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>

GiteaMirror added the pull-request label 2026-05-06 12:50:25 -05:00

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Reference: github-starred/open-webui#66463