bpo-31061: fix crash in asyncio speedup module (GH-2966)

Lib/test/test_asyncio/test_futures.py

 """Tests for futures.py."""
 
 import concurrent.futures
+import gc
 import re
 import sys
 import threading
@@ -19,9 +20,11 @@ except ImportError:
 def _fakefunc(f):
     return f
 
+
 def first_cb():
     pass
 
+
 def last_cb():
     pass
 
@@ -483,6 +486,15 @@ class BaseFutureTests:
                           Exception("elephant"), Exception("elephant"))
         self.assertRaises(TypeError, fi.throw, list)
 
+    def test_future_del_collect(self):
+        class Evil:
+            def __del__(self):
+                gc.collect()
+
+        for i in range(100):
+            fut = self._new_future(loop=self.loop)
+            fut.set_result(Evil())
+
 
 @unittest.skipUnless(hasattr(futures, '_CFuture'),
                      'requires the C _asyncio module')

Lib/test/test_asyncio/test_tasks.py

@@ -3,6 +3,7 @@
 import collections
 import contextlib
 import functools
+import gc
 import io
 import os
 import re
@@ -91,6 +92,20 @@ class BaseTaskTests:
         self.loop.set_task_factory(self.new_task)
         self.loop.create_future = lambda: self.new_future(self.loop)
 
+    def test_task_del_collect(self):
+        class Evil:
+            def __del__(self):
+                gc.collect()
+
+        @asyncio.coroutine
+        def run():
+            return Evil()
+
+        self.loop.run_until_complete(
+            asyncio.gather(*[
+                self.new_task(self.loop, run()) for _ in range(100)
+            ], loop=self.loop))
+
     def test_other_loop_future(self):
         other_loop = asyncio.new_event_loop()
         fut = self.new_future(other_loop)

Misc/NEWS.d/next/Library/2017-08-01-09-32-58.bpo-31061.husAYX.rst

+Fixed a crash when using asyncio and threads.

Modules/_asynciomodule.c

@@ -972,6 +972,8 @@ FutureObj_dealloc(PyObject *self)
         }
     }
 
+    PyObject_GC_UnTrack(self);
+
     if (fut->fut_weakreflist != NULL) {
         PyObject_ClearWeakRefs(self);
     }
@@ -1846,6 +1848,8 @@ TaskObj_dealloc(PyObject *self)
         }
     }
 
+    PyObject_GC_UnTrack(self);
+
     if (task->task_weakreflist != NULL) {
         PyObject_ClearWeakRefs(self);
     }