flatpak breaks the assumption that no two processes can have the same pid while running

[cmollekopf]

Linux distribution and version

All

Flatpak version

All

Description of the problem

flatpak breaks the assumption that no two processes can have the same pid while running,
Point in case: https://phabricator.kde.org/T8063
The problem is that the files are shared but the pid-space is not.

This is perhaps rather a documentation issue than something that can be solved.
Another approach would be to allow a flatpak to specify that only a single instance can ever run.
Or of course, don't break the assumption, but I doubt that's feasible.

Don't know if this is an issue that affects other applications, but it's something to be aware of.

Steps to reproduce

[matthiasclasen]

ever since the appearance of pid namespaces in the kernel, that is not a valid assumption anymore

[cmollekopf]

Right, thanks for the clarification.