# Benchmarks

Independent TechEmpower benchmarks show **FastAPI** applications running under Uvicorn as <a href="https://www.techempower.com/benchmarks/#section=test&runid=7464e520-0dc2-473d-bd34-dbdfd7e85911&hw=ph&test=query&l=zijzen-7" class="external-link" target="_blank">one of the fastest Python frameworks available</a>, only below Starlette and Uvicorn themselves (used internally by FastAPI).

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    //
    // p4 inherits from p3
    // p3 inherits from p2
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    // p1 inherits from p0
    // p0 inherits from super model
    //
    // or we can show it graphically as:
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    // p4 ---> p3 ---> p2 ---> p1 ---> p0 --> super model
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    @Test

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    //
    // p4 inherits from p3
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    // or we can show it graphically as:
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    @Test

{* ../../docs_src/dataclasses/tutorial002.py hl[1,7:13,19] *}

The dataclass will be automatically converted to a Pydantic dataclass.

This way, its schema will show up in the API docs user interface:

<img src="/img/tutorial/dataclasses/image01.png">

## Dataclasses in Nested Data Structures

// to the appropriate UI error.
func ErrorToErr(err error) Err {
	if err == nil {
		return Err{}
	}

	// If this is already a Err, do nothing
	if e, ok := err.(Err); ok {
		return e
	}

	// Show a generic message for known golang errors
	if errors.Is(err, syscall.EADDRINUSE) {
		return ErrPortAlreadyInUse(err).Msg("Specified port is already in use")

border-color: #007bff;\n}\n\n.btn-primary:not(:disabled):not(.disabled):active, .btn-primary:not(:disabled):not(.disabled).active,\n.show > .btn-primary.dropdown-toggle {\n  color: #fff;\n  background-color: #0062cc;\n  border-color: #005cbf;\n}\n\n.btn-primary:not(:disabled):not(.disabled):active:focus, .btn-primary:not(:disabled):not(.disabled).active:focus,\n.show > .btn-primary.dropdown-toggle:focus {\n  box-shadow: 0 0 0 0.2rem rgba(38, 143, 255, 0.5);\n}\n\n.btn-secondary {\n  color: #fff;\n...

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