$ perl -de1

Loading DB routines from perl5db.pl version 1.37
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(-e:1):   1
  DB<1> $x = "x" x 1_000_000_000

  DB<2> p $$
1139 # --> `top -p 1139` in anderem Shellfenster: 1 GB VIRT
  DB<2> undef $x
# top: 32 KB VIRT
  DB<6> $DB::x="test"

  DB<7> p $DB::x ne $x
1 # $x kann intern nur lexikal sein, oder?