@Marvin does the prefect 2.x

ConcurrentTaskRunner

use fork or spawn for multiprocessing

The

ConcurrentTaskRunner

in Prefect 2.x uses a thread pool maintained by

anyio

for concurrency. It does not use multiprocessing with fork or spawn; instead, it allows tasks to switch when blocking on IO. If you are looking for parallel execution using multiprocessing, you might consider using the

DaskTaskRunner

or

RayTaskRunner

for distributed task execution. For more details, you can visit the Prefect 2.x task runners documentation.