Deadlock¶

https://pythonspeed.com/articles/python-multiprocessing/

In Python 3 the multiprocessing library added new ways of starting subprocesses. One of these does a fork() followed by an execve() of a completely new Python process.

global¶

from multiprocessing import set_start_method
set_start_method("spawn")

local¶

from multiprocessing import get_context
def your_func():
    with get_context("spawn").Pool() as pool:
        # ... everything else is unchanged

Start Method¶

A start method is the technique used to start child processes in Python.

• spawn: start a new Python process.

• fork: copy a Python process from an existing process.

• forkserver: new process from which future forked processes will be copied.

default Start Methods¶

• Windows (win32): spawn

• macOS (darwin): spawn

• Linux (unix): fork