An important point that nobody has pointed out:

$myArray["service1"]
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For learning and playing around with data structures like this I recommend using Data::Dumper so you can easily see what Perl really has done (which may be very different from what you think it is doing).

This code will recurse through the elements, and print the number of array-elements for each array in your structure. Will not decent hashes but can be hacked a bit to do that as well.

use strict;
 
my @a = ([([0..3] ) x 4]) x 3;
 
arraylength( \@a );
 
sub arraylength{
  my $a = shift;
  my $dim = 0;
  _length( $a, $dim );
}
 
sub _length{
  my $a = shift;
  my $dim = shift;
  if ( ref( $a ) =~ /ARRAY/ ){
    print "\t" x $dim;
    print "dim $dim -> ".(scalar @$a)." elements";
    print "\n\n" if $dim == 0;
    print "\n" if $dim == 1;
    _length( $_, $dim + 1) for ( @$a );
    print "\n";
  }
}
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dim 0 -> 3 elements
 
        dim 1 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
 
        dim 1 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
 
        dim 1 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
                dim 2 -> 4 elements
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In a perl array of arrays, just like in C, the data structure does not have to be rectangular (or cuboidal, or ...). For example, you can have an array like so:

@foo = (
    [0, 1, 2, 3, 4, 5],
    [0, 1, 2],
    [0, [ 0, 1, 2, 3 ]]
);
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my @foo = (
    [0, 1, 2, 3, 4, 5],
    [0, 1, 2],
    [0, [ 0, 1, 2, 3 ]]
);

my @maxlength = ();
figger_out_depth(0, @foo);

print "max dimensions:\n";
print "  $_: $maxlength[$_]\n" foreach (0..$#maxlength);

sub figger_out_depth {
    my $depth = shift;
    $maxlength[$depth] = 0 unless(defined($maxlength[$depth]));
    foreach my $element (@_) {
        figger_out_depth($depth + 1, @{$element}) if(ref($element) eq 
+'ARRAY');
    }
    $maxlength[$depth] = $#_ + 1 if($#_ >= '0'.$maxlength[$depth]);
}
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I made this subroutine for work so I guess it's more specific than the other two answers, but I find that this one can be modified and understood far easier than the others:

#this prints 0
print getSecondArraySize("la", %test)."\n";

# put stuff in
$test{"la"}[0] = "1";
$test{"la"}[1] = "2";
$test{"la"}[2] = "3";

#this prints 3
print getSecondArraySize("la", %test)."\n";
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And here's the code:

##########################################################
# subroutine getSecondArraySize
# Parameter: An associative array containing scalar 
#            array and the name of a key
# Returns the total amount of element(s) in the scalar
# array within the associative array at the key location
# index
##########################################################
sub getSecondArraySize {

    # receives the argument
    my ($index, %array_to_count) = @_;
    
    # create the variable and get the number
    my $count=0;
    
    # determine the total amount of elements in the array    
    while (defined($array_to_count{$index}[$count])) {
       $count++;
    }   
    return $count;    
}
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