Ubuntu Platform Notes
This topic includes the information on the following adjustments:
Semaphore Deletion Setting
Under some circumstances, the OS may delete an instance’s semaphores when the instance owner connects to an Ubuntu host, for example using SSH. To prevent this, edit the /etc/systemd/logind.conf file and change RemoveIPC=yes (the default) to RemoveIPC=no.
Updating to a newer version of Ubuntu may revert RemoveIPC to the default value of yes. After updating Ubuntu, be sure to change RemoveIPC to avoid unwanted semaphore deletion.