use Data::Dumper;
 
$copy=1; #what you want?
 
%threads=(
	  keyA => [ 2, 6, 8 ],
	  keyB => [ 3, 5, 10, 14, 18 ],
	 );
 
$tnum=0;
foreach $thread (keys %threads) {
	$tsub[$tnum]      = $thread;	
	$tlist[$tnum]     = $threads{$thread}    unless $copy;
	@{$tlist[$tnum]}  = @{$threads{$thread}} if $copy;
	$tsize[$tnum]     = @{$tlist[$tnum]};	
	$tnum++;
}
 
print Dumper \@tsub,\@tlist,\@tsize;