Here I'll show you how to use **Uvicorn** with **worker processes** using the `fastapi` command or the `uvicorn` command directly.

/// info

If you are using containers, for example with Docker or Kubernetes, I'll tell you more about that in the next chapter: [FastAPI in Containers - Docker](docker.md){.internal-link target=_blank}.

* Processing data:
    * For example, let's say you receive a file that must go through a slow process, you can return a response of "Accepted" (HTTP 202) and process the file in the background.

## Using `BackgroundTasks` { #using-backgroundtasks }

First, import `BackgroundTasks` and define a parameter in your *path operation function* with a type declaration of `BackgroundTasks`:

            ListTestSuiteBuilder.using(new ShortsAsListGenerator()).named("Shorts.asList"),
            ListTestSuiteBuilder.using(new ShortsAsListHeadSubListGenerator())
                .named("Shorts.asList, head subList"),
            ListTestSuiteBuilder.using(new ShortsAsListTailSubListGenerator())
                .named("Shorts.asList, tail subList"),
            ListTestSuiteBuilder.using(new ShortsAsListMiddleSubListGenerator())

            ListTestSuiteBuilder.using(new LongsAsListGenerator()).named("Longs.asList"),
            ListTestSuiteBuilder.using(new LongsAsListHeadSubListGenerator())
                .named("Longs.asList, head subList"),
            ListTestSuiteBuilder.using(new LongsAsListTailSubListGenerator())
                .named("Longs.asList, tail subList"),
            ListTestSuiteBuilder.using(new LongsAsListMiddleSubListGenerator())

Nevertheless, you can still do it in **FastAPI**, using one of the internal tools from Starlette.

And the docs would still work, although not adding any documentation telling that the parameter should contain a path.

### Path convertor { #path-convertor }

Using an option directly from Starlette you can declare a *path parameter* containing a *path* using a URL like:

```
/files/{file_path:path}
```

                     TF_Status* status) {
  using tensorflow::NodeDef;
  using tensorflow::OpRegistrationData;
  using tensorflow::Tensor;
  using tensorflow::shape_inference::DimensionHandle;
  using tensorflow::shape_inference::InferenceContext;
  using tensorflow::shape_inference::ShapeAndType;
  using tensorflow::shape_inference::ShapeHandle;

  const int num_inputs = input_shapes->num_items;

	if _, err := sio.Encrypt(&buffer, bytes.NewReader(etag), sio.Config{Key: mac.Sum(nil)}); err != nil {
		logger.CriticalIf(context.Background(), errors.New("Unable to encrypt ETag using object key"))
	}
	return buffer.Bytes()
}

// UnsealETag unseals the etag using the provided object key.
// It does not try to decrypt the ETag if len(etag) == 16
// because such ETags indicate that the S3 client hasn't sent

In version 0.121.0, FastAPI added support for `Depends(scope="function")` for dependencies with `yield`.

Using `Depends(scope="function")`, the exit code after `yield` is executed right after the *path operation function* is finished, before the response is sent back to the client.

And when using `Depends(scope="request")` (the default), the exit code after `yield` is executed after the response is sent.

### Data protection

import java.time.Instant;
import java.time.ZoneId;
import java.time.ZoneOffset;

/**
 * A Clock implementation that combines monotonic timing with wall-clock time.
 * <p>
 * This class provides precise time measurements using {@link System#nanoTime()}
 * while maintaining wall-clock time information in UTC. The wall-clock time
 * is computed from the monotonic duration since system start to ensure consistency
 * between time measurements.
 * <p>