Where you have circular reference, i.e., your reference graph contains
loops. Unless you are so poor on memory that you manually unset variables
in the course of the script, you shouldn't really care when variable
memory is cleaned - on executor engine shutdown or on memory engine
shutdown. Those that are "leaks" are just cleaned on memory engine
shutdown. These leaks are not good because in general case they could
accumulate, but the circular reference ones are pretty hard to make
accumulating (you should really do a lot of short-living circular
referenced structures, while unsetting them manually all the time), and I
saw no single real case where it could really hurt performance.
ok. zeev mentioned that similar before... to let end this, just a small example, that´s the most trivial circular reference I know of, when and where (and how much) leaks are generated here:
$x->x=&$x;
var_dump($x);
thx for you patience
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