multiprocessing, default assumption of Pool size unhelpful

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2018-03-02.17:51:29.312>
labels = ['3.8', 'type-feature', 'library']
title = 'multiprocessing, default assumption of Pool size unhelpful'
updated_at = <Date 2019-02-26.07:54:27.392>
user = 'https://github.com/mj-harvey'

bugs.python.org fields:

activity = <Date 2019-02-26.07:54:27.392>
actor = 'eryksun'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2018-03-02.17:51:29.312>
creator = 'M J Harvey'
dependencies = []
files = []
hgrepos = []
issue_num = 32986
keywords = ['patch']
message_count = 12.0
messages = ['313150', '313381', '313382', '313385', '313386', '313387', '313392', '313401', '313402', '313403', '313406', '313408']
nosy_count = 7.0
nosy_names = ['pitrou', 'njs', 'eryksun', 'davin', 'Matthew Rocklin', 'Matt Harvey', 'M J Harvey']
pr_nums = ['5959']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue32986'
versions = ['Python 3.8']