Consider adding a parserservice dedicated to restoring linked entities
The first parser service will always have to care for restoring the various FS instances and entities associated with the task. For now, this ends up being done by the metadata extractor, but since this service is the slowest, we probably want to delegate this to another thread.
We might also miss a few opportunities for avoiding some database requests when the metadata extractor service gets run by 2 threads, since they probably can't share their last task information