pritesh@t430:~$ perl test.pl 
Before calling the sub test_this @arr: 1 2 3 4 5 6 7 8 9 10
Inside the sub, before the map @arr: 1 2 3 4 5 6 7 8 9 10
Inside the sub, before the map @_ = 1 2 3 4 5 6 7 8 9 10
Inside the sub, after the map @arr: 2 4 6 8 10 12 14 16 18 20
Inside the sub, after the map @_ = 2 4 6 8 10 12 14 16 18 20
After calling the sub test_this @arr: 2 4 6 8 10 12 14 16 18 20
pritesh@t430:~$