[issue21435] Segfault with cyclic reference and asyncio.Future

[Peter Inglesby]

New submission from Peter Inglesby:

The following code causes a segfault when run under Python3.4+ on OSX10.9.

# segfaulter.py
import asyncio
 
class A:
    pass
 
class B:
    def __init__(self, future):
        self.future = future
 
    def __del__(self):
        self.a = None
 
@asyncio.coroutine
def do_work(future):
    a = A()
    b = B(asyncio.Future())
 
    a.b = b
    b.a = a
 
    future.set_result(None)
 
future = asyncio.Future()
asyncio.Task(do_work(future))
loop = asyncio.get_event_loop()
loop.run_until_complete(future)


It does matter that the Future is passed to b's __init__ method.

It doesn't matter whether the Future has been resolved.

Attached is the problem report generated by OSX on the crash.

----------
files: problemreport.txt
messages: 217918
nosy: inglesp
priority: normal
severity: normal
status: open
title: Segfault with cyclic reference and asyncio.Future
type: crash
versions: Python 3.4, Python 3.5
Added file: http://bugs.python.org/file35152/problemreport.txt

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<http://bugs.python.org/issue21435>
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