Do I run the risk of exhausting the system resources?

Maybe, depends on how much memory you have, how much of memory your perl program is allocated, and the size of the logs --- I can't imagine 1GB of logs being generated

However, when running these types of things, I usually try to use a logfile option (i don't know if rdiff-backup has one) , or at least auto create a log, like

...  > thing-date-time.log 2>&1
...  1> thing-date-time-1.log   2> thing-date-time-1.log

...  1> thing-date-time-stdout.log   2> thing-date-time-stderr.log
[download]

where date-time is either time or a iso-8601 timestamp (eg 2011-03-02T001131-0800 )