[dangit, had Control down when I hit <enter> and it sent prematurely]
On 2015-05-02 13:02, vasudevram wrote: > http://jugad2.blogspot.in/2015/05/can-python-data-structure-reference.html > > https://docs.python.org/2/reference/datamodel.html > > and saw this excerpt: > > [ CPython implementation detail: CPython currently uses a > reference-counting scheme with (optional) delayed > detection of cyclically linked garbage, which collects > most objects as soon as they become unreachable, but is > not guaranteed to collect garbage containing circular > references. ] > > Not sure whether it is relevant to the topic at hand, > since, on the one hand, it uses the words "cyclically > linked", but on the other, it says "garbage collection". The gotcha happens in a case where you do something like this: lst = [] lst.append(lst) # create a cycle del lst This creates a cycle, then makes it unreachable, but the list is still referenced by itself, so the reference count never drops to zero (where it would get GC'd), and thus that item lingers around in memory. If you know that you're creating such cyclical structures, it's best to manually unlink them before freeing them: lst = [] lst.append(lst) # create the cycle lst[:] = [] # break the cycle # or lst.remove(lst) # though this takes more care del lst -tkc -- https://mail.python.org/mailman/listinfo/python-list
