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()
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Deleting the CLA section will lead to immediate closure of your PR and it will not be merged in.
🔄 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:** ✅ Merged
**Merged:** 5/8/2026
**Merged by:** [@tjbck](https://github.com/tjbck)
**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
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- [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]
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<sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>
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📋 Pull Request Information
Original PR: https://github.com/open-webui/open-webui/pull/24338
Author: @Classic298
Created: 5/3/2026
Status: ✅ Merged
Merged: 5/8/2026
Merged by: @tjbck
Base:
dev← Head:fix/stt-blocking-event-loop📝 Commits (1)
eec14f1fix: 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
Contributor License Agreement
🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.