In util-linux-2.32, unshare --pid --kill-child uses a pid namespace to implement behavior like FEATURES=cgroup, which has the advantage that there's no need for special interaction with systemd as discussed in bug 602706.
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/proj/portage.git/commit/?id=88ba0f45b54609666445c7f8008ff699eef52b39 commit 88ba0f45b54609666445c7f8008ff699eef52b39 Author: Michał Górny <mgorny@gentoo.org> AuthorDate: 2018-11-11 11:48:24 +0000 Commit: Michał Górny <mgorny@gentoo.org> CommitDate: 2018-11-18 12:24:52 +0000 Support FEATURES=pid-sandbox Supporting using PID namespace in order to isolate the ebuild processes from host system, and make it possible to kill them all easily (similarly to cgroups but easier to use). Bug: https://bugs.gentoo.org/659582 Reviewed-by: Zac Medico <zmedico@gentoo.org> Signed-off-by: Michał Górny <mgorny@gentoo.org> lib/portage/const.py | 1 + lib/portage/package/ebuild/doebuild.py | 8 ++++-- lib/portage/process.py | 48 ++++++++++++++++++++++++++++++---- man/make.conf.5 | 7 +++++ 4 files changed, 57 insertions(+), 7 deletions(-)
Fixed in portage-2.3.62.