in reply to Does undef free ram?
I think undef will be fine if you are dumping the hash or array.
Also how many elements are you talking about? I have to ask because one of my partners was concerned about the same thing and he had 100 elements? ;)
Many machines these days have tons of ram and it quickly recovers stuff once a job completes. So it is good to be clean but don't get too freeked out unless of course you have gigantic arrays and hashes.
Just my .02
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