sub read_file {
    my $url = shift;
    my $file_data;
    open my $fh, '<', $url;
    local $/;
    $file_data = <$fh>;
    show_size();
}

show_size();
read_file('name1.txt');
read_file('name2.txt');
read_file('name3.txt');
read_file('name4.txt');
read_file('name5.txt');
show_size();

sub show_size {
    print `top -l 1 | grep perl | awk '{print "MEM="\$8 "\tRPRVT="\$30}'`; # Work on Mac OS X 10.10
}

##</code><code>##

sub read_file {
    my $url = shift;
    my $file_data = [];
    open my $fh, '<', $url;
    local $/;
    $file_data->[0] = <$fh>;
    show_size();
}

show_size();
read_file('name1.txt');
read_file('name2.txt');
read_file('name3.txt');
read_file('name4.txt');
read_file('name5.txt');
show_size();

sub show_size {
    print `top -l 1 | grep perl | awk '{print "MEM="\$8 "\tRPRVT="\$30}'`; # Work on Mac OS X 10.10
}