Add section about event loop (#2725)

Author: Kludex

docs/concepts/event-loop.md

@@ -0,0 +1,75 @@
+# Event Loop
+
+Uvicorn provides two event loop implementations that you can choose from using the [`--loop`](../settings.md#implementation) option:
+
+```bash
+uvicorn main:app --loop <auto|asyncio|uvloop>
+```
+
+By default, Uvicorn uses `--loop auto`, which automatically selects:
+
+1. **uvloop** - If [uvloop](https://github.com/MagicStack/uvloop) is installed, Uvicorn will use it for maximum performance
+2. **asyncio** - If uvloop is not available, Uvicorn falls back to Python's built-in asyncio event loop
+
+Since `uvloop` is not compatible with Windows or PyPy, it is not available on these platforms.
+
+On Windows, the asyncio implementation uses [`ProactorEventLoop`][asyncio.ProactorEventLoop] if running with multiple workers,
+otherwise it uses the standard [`SelectorEventLoop`][asyncio.SelectorEventLoop] for better performance.
+
+??? info "Why does `SelectorEventLoop` not work with multiple processes on Windows?"
+    If you want to know more about it, you can read the issue [#cpython/122240](https://github.com/python/cpython/issues/122240).
+
+## Custom Event Loop
+
+You can use custom event loop implementations by specifying a module path and function name using the colon notation:
+
+```bash
+uvicorn main:app --loop <module>:<function>
+```
+
+The function should return a callable that creates a new event loop instance.
+
+### rloop
+
+[rloop](https://github.com/gi0baro/rloop) is an experimental AsyncIO event loop implemented in Rust on top of the [mio](https://github.com/tokio-rs/mio) crate. It aims to provide high performance through Rust's systems programming capabilities.
+
+You can install it with:
+
+=== "pip"
+    ```bash
+    pip install rloop
+    ```
+=== "uv"
+    ```bash
+    uv add rloop
+    ```
+
+You can run `uvicorn` with `rloop` with the following command:
+
+```bash
+uvicorn main:app --loop rloop:new_event_loop
+```
+
+!!! warning "Experimental"
+    rloop is currently **experimental** and **not suited for production usage**. It is only available on **Unix systems**.
+
+### Winloop
+
+[Winloop](https://github.com/Vizonex/Winloop) is an alternative library that brings uvloop-like performance to Windows. Since uvloop is based on libuv and doesn't support Windows, Winloop provides a Windows-compatible implementation with significant performance improvements over the standard Windows event loop policies.
+
+You can install it with:
+
+=== "pip"
+    ```bash
+    pip install winloop
+    ```
+=== "uv"
+    ```bash
+    uv add winloop
+    ```
+
+You can run `uvicorn` with `Winloop` with the following command:
+
+```bash
+uvicorn main:app --loop winloop:new_event_loop
+```

mkdocs.yml

@@ -56,6 +56,7 @@ nav:
       - ASGI: concepts/asgi.md
       - Lifespan: concepts/lifespan.md
       - WebSockets: concepts/websockets.md
+      - Event Loop: concepts/event-loop.md
   - Deployment:
       - Deployment: deployment/index.md
       - Docker: deployment/docker.md
@@ -98,11 +99,8 @@ plugins:
   - mkdocstrings:
       handlers:
         python:
-          import:
-            - url: https://docs.python.org/3/objects.inv
-
-plugins:
-  - search
+          inventories:
+            - https://docs.python.org/3/objects.inv
   - llmstxt:
       full_output: llms-full.txt
       markdown_description: |-