There seems to be a memory leak somewhere (maybe not technically a 'memory leak' since you are using Python but), phoenix uses several hundred megabytes of ram after several days of running.  My guess is a failure to prune some sort of list of completed shares / console output / something.  I would simply quit and restart, but I've run into the previously mentioned bug where my normally stable system would completely freeze upon exiting phoenix.  This one I can't seem to reliably reproduce, it happens sometimes upon exiting but most of the time it's fine.