commit 5dbb1b7df1d9ecaa6b5344028cd1777502cf5c73
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Sat Oct 13 12:26:47 2018 -0700
committer Andrew Svetlov <andrew.svetlov@gmail.com> Sat Oct 13 22:26:47 2018 +0300
tree 310d5ea9f721525c7a49a6d93dd5af323035121a
parent d07564274a120030275ea17859458838c1513694

bpo-34970: Protect tasks weak set manipulation in asyncio.all_tasks() (GH-9837) (GH-9849)

https://bugs.python.org/issue34970
(cherry picked from commit 97cf0828727ac2a269c89c5aa09570a69a22c83c)

Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

Lib/asyncio/tasks.py

diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index 72792a2..416c346 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -35,7 +35,9 @@
     """Return a set of all tasks for the loop."""
     if loop is None:
         loop = events.get_running_loop()
-    return {t for t in _all_tasks
+    # NB: set(_all_tasks) is required to protect
+    # from https://bugs.python.org/issue34970 bug
+    return {t for t in list(_all_tasks)
             if futures._get_loop(t) is loop and not t.done()}
 
 
@@ -45,7 +47,9 @@
     # method.
     if loop is None:
         loop = events.get_event_loop()
-    return {t for t in _all_tasks if futures._get_loop(t) is loop}
+    # NB: set(_all_tasks) is required to protect
+    # from https://bugs.python.org/issue34970 bug
+    return {t for t in list(_all_tasks) if futures._get_loop(t) is loop}
 
 
 class Task(futures._PyFuture):  # Inherit Python Task implementation