Speed up rororo applications

There are several known ways of improving performance for rororo applications.

[startup] Custom schema loader

In most cases you may ignore speeding up startup of aiohttp.web application, the place where rororo.openapi.setup_openapi() called. But, as loading schema dict from file is time consuming operation (especially when OpenAPI schema file is large or disk, where file is stored, is slow) there are several techniques on how to faster load OpenAPI schema.

YAML files

Ensure that libyaml is installed in your system. After, yaml.CSafeLoader will be used instead of yaml.SafeLoader, which might increase load time up to 10 times.

In [1]: import yaml

In [2]: from api.constants import PROJECT_PATH

In [3]: schema_path = PROJECT_PATH / "openapi.yaml"

In [4]: %timeit yaml.load(schema_path.read_text(), Loader=yaml.SafeLoader)
164 ms ± 10.1 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

In [5]: %timeit yaml.load(schema_path.read_text(), Loader=yaml.CSafeLoader)
14.6 ms ± 339 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

JSON files

rororo.openapi.setup_openapi() allows to pass custom schema loader function, as by default, for JSON files, it uses standard json.loads(), which is not the fastest way of loading JSON files into the Python.

Example below illustrates how to use ujson for loading schema from openapi.json file,

from pathlib import Path

import ujson
from aiohttp import web
from rororo import setup_openapi

from .views import operations

app = setup_openapi(
    Path(__file__) / "openapi.json",

[runtime] Disable validating responses

To satisfy that OpenAPI hander provides proper response rororo internally run ResponseValidator.validate(...) function.

In most cases this fact is OK as it will ensure that all responses conform OpenAPI schema and client will receive expected result. However, it also results in extra deserializing / validation calls, which will slow down process of getting response from OpenAPI handler.

To “fix” this, there is a possibility to entirely turn off validation of responses in rororo,

app = setup_openapi(
    Path(__file__) / "openapi.yaml",


Turning off response validation may cause unexpected results for application consumers.

[testing] Cache reading schema and spec creation

If you have a lot of tests and many of them calling rororo.openapi.setup_openapi() before supplying web.Application to aiohttp_client you might want to speed up things, by caching calls for,

  • rororo.openapi.openapi.read_openapi_schema()

  • openapi_core.shortcuts.create_spec()

To enable this behaviour use next snippet,

from pathlib import Path

from rororo import (

app = setup_settings_from_environ(
    web.Application(), BaseSettings
    Path(__file__) / "openapi.yaml",