[PR #23705] [MERGED] fix(retrieval): offload Loader.load to a worker thread so file uploads stop blocking the event loop #130990

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GiteaMirror · 2026-05-21T15:52:00-05:00

GiteaMirror commented

2026-05-21 15:52:00 -05:00

📋 Pull Request Information

Original PR: https://github.com/open-webui/open-webui/pull/23705
Author: @Classic298
Created: 4/14/2026
Status: ✅ Merged
Merged: 4/14/2026
Merged by: @tjbck

Base: dev ← Head: claude/fix/loader-aload-async

📝 Commits (1)

62523fe fix(retrieval): offload Loader.load to a worker thread so file uploads stop blocking the event loop

📊 Changes

2 files changed (+14 additions, -1 deletions)

View changed files

📝 backend/open_webui/retrieval/loaders/main.py (+13 -0)
📝 backend/open_webui/routers/retrieval.py (+1 -1)

📄 Description

Loader.load() dispatches to the underlying langchain document loaders (PyMuPDF, Unstructured, python-docx, Tika, …) which are all synchronous and CPU/IO-bound. process_file() awaited it directly on the event loop, so parsing a non-trivial PDF/DOCX would freeze the entire FastAPI app for the duration of the parse — which is what users experience as "the server hangs whenever I upload a file."

Add an aload() async wrapper on Loader that runs the sync load on a worker thread via asyncio.to_thread, and update process_file() to await it. The sync API is preserved so existing callers that already run inside run_in_threadpool (e.g. save_docs_to_vector_db) are unaffected.

Contributor License Agreement

By submitting this pull request, I confirm that I have read and fully agree to the Contributor License Agreement (CLA), 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.

_{🔄 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/23705 **Author:** [@Classic298](https://github.com/Classic298) **Created:** 4/14/2026 **Status:** ✅ Merged **Merged:** 4/14/2026 **Merged by:** [@tjbck](https://github.com/tjbck) **Base:** `dev` ← **Head:** `claude/fix/loader-aload-async` --- ### 📝 Commits (1) - [`62523fe`](https://github.com/open-webui/open-webui/commit/62523fe0ba37d748be76c6cb76453acf6c1be36c) fix(retrieval): offload Loader.load to a worker thread so file uploads stop blocking the event loop ### 📊 Changes **2 files changed** (+14 additions, -1 deletions) <details> <summary>View changed files</summary> 📝 `backend/open_webui/retrieval/loaders/main.py` (+13 -0) 📝 `backend/open_webui/routers/retrieval.py` (+1 -1) </details> ### 📄 Description Loader.load() dispatches to the underlying langchain document loaders (PyMuPDF, Unstructured, python-docx, Tika, …) which are all synchronous and CPU/IO-bound. process_file() awaited it directly on the event loop, so parsing a non-trivial PDF/DOCX would freeze the entire FastAPI app for the duration of the parse — which is what users experience as "the server hangs whenever I upload a file." Add an `aload()` async wrapper on Loader that runs the sync load on a worker thread via asyncio.to_thread, and update process_file() to await it. The sync API is preserved so existing callers that already run inside run_in_threadpool (e.g. save_docs_to_vector_db) are unaffected. ### 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 2026-05-21 15:52:00 -05:00

GiteaMirror closed this issue

2026-05-21 15:52:04 -05:00

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Reference: github-starred/open-webui#130990