I came back to my computer after leaving Renoise open for a few days and the Log.txt file had bloated to 60GB and filled up the rest of my hard drive space. It seems Renoise had been writing the following error message over and over:
MIDI-IO: Failed to flush the ALSA sequencer event queue (error: Resource temporarily unavailable)!!
I would expect there to be some guard to stop a repeating error message from filling up all hard drive space.