Uh. You wanna keep two lists: one full of URLs queued for crawling and the other with those you successfully visited (this one will be searched on each iteration so let it be hash). So the logic is: 
sub crawl {
    my @queue = @_;
    my %visited;

    while(my $url = shift @queue) {
        next if $visited{$url};

        my $content = $http_ua->get($url);
        # do useful things with $content

        push @queue, $link_extractor->links($content);
        $visited{$url} = 1;
    }
}

[download]

That's all. When size and efficiency start to really matter you will evaluate migrating data to something like Cache::Cache or Berkeley DB.

In reply to Re: Cutting Out Previously Visited Web Pages in A Web Spider by kappa
in thread Cutting Out Previously Visited Web Pages in A Web Spider by mkurtis

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