FreeBSD, Jails and SYSV IPC
I run all my stuff in FreeBSD jails which used to make things even more complicated, because
SYSV IPC
stuff wasn't namespaced, so two jails withallow.sysvipc=1
could see and modify each others shared memory and semaphores - not ideal. In FreeBSD 11 and beyond this is no longer an issue, as I will demonstrate later in this post.
Source: FreeBSD, Jails and SYSV IPC, an article by Thomas Steen Rasmussen.