Using undef will also free the memory for use in other parts of your program. However, it's not nearly as safe as using my because my properly cleans up when return and die are used. The second quote is neither incorrect nor misleading.

Sorry, I think you've got it wrong. Lexical (my) variables do not free their memory when they go out of scope. That's what the first FAQ is saying, and it agrees with what many others have said here and elsewhere. For example, see this node by Dan Sugalski.

I see what you mean

use Devel::Peek qw( Dump );

{ my $v1 = "test"; Dump($v1); }
{ my $v2 = "test"; Dump($v2); }
{ my $v3 = "test"; Dump($v3); }

__END__
SV = PV(0x1abea7c) at 0x1ab2710
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK)
  PV = 0x1aa01f4 "test"\0            0x1aa01f4
  CUR = 4
  LEN = 5
SV = PV(0x1abea94) at 0x1ab26f8
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK)
  PV = 0x1aa01e4 "test"\0            0x1aa01e4
  CUR = 4
  LEN = 5
SV = PV(0x1abeaac) at 0x1ab2734
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK)
  PV = 0x1aa01d4 "test"\0            0x1aa01d4
  CUR = 4
  LEN = 5
[download]

vs

use Devel::Peek qw( Dump );

{ my $v1 = "test"; Dump($v1); undef $v1; }
{ my $v2 = "test"; Dump($v2); undef $v2; }
{ my $v3 = "test"; Dump($v3); undef $v3; }

__END__
SV = PV(0x1abea7c) at 0x1ab26d4
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK)
  PV = 0x1aa01f4 "test"\0            0x1aa01f4
  CUR = 4
  LEN = 5
SV = PV(0x1abea94) at 0x1ab26f8
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK)
  PV = 0x1aa01f4 "test"\0            0x1aa01f4
  CUR = 4
  LEN = 5
SV = PV(0x1abeaac) at 0x1ab26c8
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK)
  PV = 0x1aa01f4 "test"\0            0x1aa01f4
  CUR = 4
  LEN = 5
[download]