Issue 38520: There is no proper way to know if a process is the main one

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/82701

classification

Title:	There is no proper way to know if a process is the main one
Type:	enhancement	Stage:	patch review
Components:	Library (Lib)	Versions:

process

Status:	open	Resolution:
Dependencies:		Superseder:
Assigned To:		Nosy List:	Delgan, ZackerySpytz, davin, pablogsal, pitrou
Priority:	normal	Keywords:	patch

Created on 2019-10-18 20:48 by Delgan, last changed 2022-04-11 14:59 by admin.

Pull Requests
URL	Status	Linked	Edit
PR 23621	open	ZackerySpytz, 2020-12-02 23:59

Messages (1)
msg354918 - (view)	Author: Delgan (Delgan) *	Date: 2019-10-18 20:48
Hi. I noticed that there exists the function "threading.main_thread()", but there is no equivalent for the "multiprocessing" module. Is there a reason for this absence? These StackOverflow questions are related to this problem: - https://stackoverflow.com/questions/42283265/how-to-determine-if-running-current-process-is-parent - https://stackoverflow.com/questions/30790660/python-multiprocessing-name-of-the-main-process - https://stackoverflow.com/questions/18216050/is-there-a-way-to-check-if-a-module-is-being-loaded-by-multiprocessing-standard Current proposed solutions have flaws. It's suggested to check if "current_process().name == 'MainProcess'" but anyone can re-write the name of a process with "current_process().name = 'foobar'" so this does not seem to be a reliable solution. Another alternative is to check for the type of the process, which is different for main and child, respectively "mulitprocessing.process._MainProcess" and "multiprocessing.process.Process". This is obviously hacky as it relies on implementation detail. What are you thoughts on adding a new "multiprocessing.main_process()" function?

msg354918 - (view)

Author: Delgan (Delgan) *

Date: 2019-10-18 20:48

Hi.

I noticed that there exists the function "threading.main_thread()", but there is no equivalent for the "multiprocessing" module.

Is there a reason for this absence?

These StackOverflow questions are related to this problem:
- https://stackoverflow.com/questions/42283265/how-to-determine-if-running-current-process-is-parent
- https://stackoverflow.com/questions/30790660/python-multiprocessing-name-of-the-main-process
- https://stackoverflow.com/questions/18216050/is-there-a-way-to-check-if-a-module-is-being-loaded-by-multiprocessing-standard

Current proposed solutions have flaws.
It's suggested to check if "current_process().name == 'MainProcess'" but anyone can re-write the name of a process with "current_process().name = 'foobar'" so this does not seem to be a reliable solution.
Another alternative is to check for the type of the process, which is different for main and child, respectively "mulitprocessing.process._MainProcess" and "multiprocessing.process.Process". This is obviously hacky as it relies on implementation detail.

What are you thoughts on adding a new "multiprocessing.main_process()" function?

History
Date	User	Action	Args
2022-04-11 14:59:21	admin	set	github: 82701
2020-12-02 23:59:25	ZackerySpytz	set	keywords: + patch nosy: + ZackerySpytz pull_requests: + pull_request22489 stage: patch review
2019-10-19 20:14:43	pablogsal	set	nosy: + pablogsal
2019-10-18 23:09:05	ned.deily	set	nosy: + pitrou, davin
2019-10-18 20:48:15	Delgan	create