move hhvm .hhbc files out of /var/run
hhvm stores a bytecode repository in .hhbc files currently under /var/run/hhvm/, which on many systems is tmpfs, ie. ram. These files grow into the hundreds of megabytes and will easily eat up the entire ramfs if many sites use hhvm, or the server has a small /var/run size. The files are read at startup and their contents are already kept memory of the hhvm process, so storing them on disk is 'fairly pointless' (https://github.com/hhvm/packaging/issues/132). Should save these on the disk, eg. maybe under /var/lib/hhvm/.
Additionally, the ispconfig init scripts currently remove the .hhbc files under the "stop" command, so it would seem that saving them at all is entirely pointless, as they are only read at startup. Should probably not remove those files under "stop", though there needs to be some handle for users to do so. Perhaps move the cleanup to a "clean" command in the init script, then run that (stop/clean/start) only when the website settings are updated/resync'd? Maybe even add a checkbox explicitly for that so production sites aren't affected by just hitting save in the control panel. And recommend in the manual that the bytecode repo be rebuilt now and then (if not force it to happen every so often, eg. if it hasn't been rebuilt in the last 100 days?)