import sys
import _overlapped
def total():
    return sys.gettotalrefcount()
if not hasattr(sys, "gettotalrefcount"):
    raise SystemExit("need a debug build (Py_DEBUG) for gettotalrefcount")
before = total()
N = 20000
STEP = 1000
for i in range(1, N + 1):
    ov = _overlapped.Overlapped()
    buf = memoryview(bytearray(4096))
    try:
        ov.WSASendTo(0x1234, buf, 0, ("127.0.0.1", 1))
    except OSError:
        pass
    if i % STEP == 0:
        now = total()
        print(f"{i:6d}: totalrefcount delta = {now - before:+d}")
after = total()
print(f"done: N={N}, totalrefcount delta = {after - before:+d}")

d:\MyCode\cpython\PCbuild\amd64>python_d.exe py_overlapped_leak.py
  1000: totalrefcount delta = +4007
  2000: totalrefcount delta = +8009
  3000: totalrefcount delta = +11906
  4000: totalrefcount delta = +15906
  5000: totalrefcount delta = +19906
......
 19000: totalrefcount delta = +75906
 20000: totalrefcount delta = +79906
done: N=20000, totalrefcount delta = +79905