The purpose of this is to ensure that the recording processing with make
visible forwards progress, by ensuring that different steps in the
recording pipeline don't block each-other.
This fixes:
- recordings being processed prevent archiving new recordings from running
- recordings can't be published until all pending recording processing
completes
It does allow recording archive, sanity, process, publish steps to run in
parallel with each other, but at most one recording will be in each step at
a time. (I.e. while one recording is being processed, a different recording
can be published). This may potentially increase CPU usage for some users.
If you expect this to be a problem, you can set resource controls (see
`man systemd.resource-control`) on the bbb_record_core.slice systemd unit.
