$ perl -de0

Loading DB routines from perl5db.pl version 1.28
Editor support available.

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

main::(-e:1):   0
  DB<1> !!ps v
  PID TTY      STAT   TIME  MAJFL   TRS   DRS   RSS %MEM COMMAND
...
 4763 pts/1    S+     0:00      0  1013  4874  4348  0.4 perl -de0
  DB<2> @array=(1..1_000_000)
  DB<3> !!ps v
  PID TTY      STAT   TIME  MAJFL   TRS   DRS   RSS %MEM COMMAND
...
 4763 pts/1    R+     0:01      0  1013 103142 102400  9.8 perl -de0