how to release used memory immediately in python list?

Question

in many cases ,you are sure you definitely won\'t use the list again,i hope the memory should be release right now

a = [11,22,34,567,9999]
del a

Answer 1

As @monkut notes, you probably shouldn't worry too much about memory management in most situations. If you do have a giant list that you're sure you're done with now and it won't go out of the current function's scope for a while, though:

del a simply removes your name a for that chunk of memory. If some other function or structure or whatever has a reference to it still, it won't be deleted; if this code has the only reference to that list under the name a and you're using CPython, the reference counter will immediately free that memory. Other implementations (PyPy, Jython, IronPython) might not kill it right away because they have different garbage collectors.

Because of this, the del a statement in your realse_list function doesn't actually do anything, because the caller still has a reference!

del a[:] will, as you note, remove the elements from the list and thus probably most of its memory usage.

You can do the_set.clear() for similar behavior with sets.

All you can do with a tuple, because they're immutable, is del the_tuple and hope nobody else has a reference to it -- but you probably shouldn't have enormous tuples!