That means $self->{'netstat_array'} is sometimes undefined, which means it doesn't contains a reference to an array.

If it's suppose to be undefined at times, then maybe you're looking for 

$self->{'netstat_array'} ||= [];
return scalar @{ $self->{'netstat_array'} }, $self->{'netstat_array'};

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In reply to Re: Can't use an undefined value as an ARRAY reference by ikegami
in thread Perl array reference error by user786

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