I read somewhere the editing /etc/security/limits.conf is now deprecated and that you should use dpkg-reconfigure -p high jack instead. The problem is the latter method doesn’t allow you to set a memory lock. I’ve got 4GB ram an would like to set the lock to 3 or 3,5 GB, but not to unlimited as it is now. How can I do that using the new method?
Unlimited should be safe, but you could always edit /etc/security/limits.d/audio.conf to your preferred amount.
Unlimited is safe until you really reach the limit, and it that case as far as I know your video could freeze because of the lack of available RAM. I thought of editing /etc/security/limits.d/audio.conf but will it interfere with the new way jack stores its settings?
dpkg has absolutely nothing to do with jack. It is a configuration tool in Debian based distributions.
Also /etc/security/limits.conf or files in /etc/security/limits.d/ don’t really have anything to do with jack. These are system configuration files (“limits.conf - configuration file for the pam_limits module” as the manpage for limits.conf says) and jack doesn’t store anything there. You put these settings there to tell your system to allow jack to run at higher priorities than it would usually allow, how much locked memory jack should be allowed to use, etc…
So the question is not if manual editing interferes with jack, but if it interferes with debians configuration tools (dpkg etc.), wich would be a question to be looked up on the net or asked at your distribution’s forums.