bug.py

import gc
import asyncio
import traceback
import inspect
loop = asyncio.get_event_loop()


class A(object):
    def __del__(self):
        print("Del A")

    async def test(self):
        res = asyncio.ensure_future(self.error())
        try:
            await res
        except Exception:
            pass

    async def error(self):
        raise Exception()

a = A()
loop.run_until_complete(a.test())
loop.close()
print("Frames which refer to a:")
print("---")
[traceback.print_stack(x) for x in gc.get_referrers(a) if inspect.isframe(x)]
print("---")
print("Refcounting:")
a = None
print("GC:")
gc.collect()

# Frames which refer to a:
# ---
#   File "bug.py", line 17, in test
#     pass
#   File "bug.py", line 20, in error
#     raise Exception()
# ---
# Refcounting:
# GC:
# Del A
# Python ending: