http://www.perlmonks.org?node_id=243025

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

How can i delete perl stuff from memory. I've understood that commands like delete, shift and undef do these. But it doesn't seem to be so. Test code below (uses ~170M memory). I watched memory usage with gtop. What happens to memory after is has been removed from perl (shift/undef/delete etc)? Can it be reused by other apps? Perl itself might be able to reuse, but i haven't tested enough to make more certain points.

#!/usr/bin/perl # # Testing memory usage... use warnings; use strict; my (%hash,@array); my ($i,$j)=(0,0); $|=1; while ($i<2000) { while ($j<1000) { push (@{$array[$i]},$j); push (@{$hash{$i+1}},$j); $j++; } $i++; $j=0; print "\r$i"; } print "\nLoaded. Sleeping little.\n"; sleep 15; print "Copying for undef.\n"; my %new_hash=%hash; print "Deleting hash.\n"; $i=0; foreach (sort {$a<=>$b} keys %hash) { delete $hash{$_}; $i++; print "\r$i"; } print "\nDone, sleeping\n"; sleep 10; print "Shifting array.\n"; $i=0; foreach (@array) { shift @array; $i++; print "\r$i"; } print "\nDone. Sleeping.\n"; sleep 10; print "Undefing new_hash.\n"; undef %new_hash; print "Sleeping.\n"; sleep 10; print "Exit.\n"; exit 0;