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create-subprocess-in-async-function (ASYNC220)#

Derived from the flake8-async linter.

What it does#

Checks that async functions do not create subprocesses with blocking methods.

Why is this bad?#

Blocking an async function via a blocking call will block the entire event loop, preventing it from executing other tasks while waiting for the call to complete, negating the benefits of asynchronous programming.

Instead of making a blocking call, use an equivalent asynchronous library or function.

Example#

async def foo():
    os.popen(cmd)

Use instead:

async def foo():
    asyncio.create_subprocess_shell(cmd)