validate_url() calls socket.getaddrinfo() for SSRF protection, which
blocks the event loop for 100-700ms per DNS lookup. This affects:
- Image generation (get_image_data) — every external image URL
- Image editing (load_url_image) — every external image URL
- OAuth profile pictures (_process_picture_url) — every login
- Webhook delivery (post_webhook) — every notification
- Image base64 conversion (get_image_base64_from_url) — chat images
Wrap all 5 async call sites in asyncio.to_thread() so DNS resolution
runs in the thread pool. The event loop remains free to serve other
requests during the lookup.
Benchmark (3 domains, 3 trials averaged):
- BEFORE: max jitter 479ms, 1 blocked ping per trial
- AFTER: max jitter 1ms, 0 blocked pings (324x improvement)
Co-authored-by: Tim Baek <tim@openwebui.com>
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