open my $fh2, '<', $file2 or die "Can't open $file2: $!"; #XX.file2 file
open my $fh3, '<', $file3 or die "Can't open $file3: $!"; #xx.file3 file
...
my @array_1 = <$fh2>;
...
my @array_4 = <$fh3>;
...
open my $fh5, '<', $file2 or die "Can't open $file2: $!"; #XX.file2 file
my @array_3 = <$fh5>;
...
open my $fh6, '<', $file3 or die "Can't open $file2: $!"; #XX.file2 file
my @array_7 = <$fh6>;