[issue21435] Segfault with cyclic reference and asyncio.Future

[Antoine Pitrou]

Antoine Pitrou added the comment:

Here is the gdb backtrace. The `gc` variable is equal to NULL.

0x000000000043d254 in finalize_garbage (collectable=0x7fffffffdc40, old=0x8fdae0 <generations+64>)
    at Modules/gcmodule.c:788
788	        if (!_PyGCHead_FINALIZED(gc) &&
(gdb) bt
#0  0x000000000043d254 in finalize_garbage (collectable=0x7fffffffdc40, old=0x8fdae0 <generations+64>)
    at Modules/gcmodule.c:788
#1  0x000000000043dac0 in collect (generation=2, n_collected=0x7fffffffdca8, n_uncollectable=0x7fffffffdcb0, nofail=0)
    at Modules/gcmodule.c:1009
#2  0x000000000043dffc in collect_with_callback (generation=2) at Modules/gcmodule.c:1128
#3  0x000000000043eda0 in PyGC_Collect () at Modules/gcmodule.c:1604
#4  0x000000000041f332 in Py_Finalize () at Python/pythonrun.c:607
#5  0x000000000043c401 in Py_Main (argc=2, argv=0x980020) at Modules/main.c:788
#6  0x000000000041af96 in main (argc=2, argv=0x7fffffffdfc8) at ./Modules/python.c:69

(gdb) p gc
$1 = (PyGC_Head *) 0x0

----------

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21435>
_______________________________________