multiprocessing is_alive() between children processes

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-12-10.23:22:54.787>
labels = ['type-bug', '3.7']
title = 'multiprocessing is_alive() between children processes'
updated_at = <Date 2019-12-10.23:22:54.787>
user = 'https://github.com/MattTimms'

bugs.python.org fields:

activity = <Date 2019-12-10.23:22:54.787>
actor = 'matttimms'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2019-12-10.23:22:54.787>
creator = 'matttimms'
dependencies = []
files = ['48770']
hgrepos = []
issue_num = 39021
keywords = []
message_count = 1.0
messages = ['358232']
nosy_count = 1.0
nosy_names = ['matttimms']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue39021'
versions = ['Python 3.7']