all Python 3sysfunction

sys.getrefcount()

memory

Returns an object's reference count. The number is usually one higher than expected: the call's own argument is a reference too.

Syntax

sys.getrefcount(object)

For a = [] the answer is 2, not 1 — getrefcount's parameter holds the second reference. Since Python 3.12 immortal objects (None, True, small ints, many strings) have a huge count that means nothing. Only 0 and 1 are reliable; free-threaded builds and 3.14 optimizations change the numbers too. It is a CPython detail: hunt leaks with gc and tracemalloc instead.

Examples

import sys
a = []
print(sys.getrefcount(a))  # → 2
b = a
print(sys.getrefcount(a))  # → 3
del b
print(sys.getrefcount(a))  # → 2

# Python 3.12+
import sys
print(sys.getrefcount(None) > 10 ** 9)  # → True — бессмертный объект

See also

Open in the full glossarydocs.python.orgReport an inaccuracy