bpo-37658: Fix asyncio.wait_for() to respect waited task status (GH-21894) (GH-21964)
Currently, if `asyncio.wait_for()` itself is cancelled it will always
raise `CancelledError` regardless if the underlying task is still
running. This is similar to a race with the timeout, which is handled
already.
(cherry picked from commit a2118a14627256197bddcf4fcecad4c264c1e39d)
Co-authored-by: Elvis Pranskevichus <elvis@magic.io>
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index 7ecec96..8b05434 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -465,9 +465,12 @@
try:
await waiter
except exceptions.CancelledError:
- fut.remove_done_callback(cb)
- fut.cancel()
- raise
+ if fut.done():
+ return fut.result()
+ else:
+ fut.remove_done_callback(cb)
+ fut.cancel()
+ raise
if fut.done():
return fut.result()
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index 511961c..74fc1e4 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -1120,6 +1120,22 @@
res = loop.run_until_complete(task)
self.assertEqual(res, "ok")
+ def test_wait_for_cancellation_race_condition(self):
+ def gen():
+ yield 0.1
+ yield 0.1
+ yield 0.1
+ yield 0.1
+
+ loop = self.new_test_loop(gen)
+
+ fut = self.new_future(loop)
+ loop.call_later(0.1, fut.set_result, "ok")
+ task = loop.create_task(asyncio.wait_for(fut, timeout=1))
+ loop.call_later(0.1, task.cancel)
+ res = loop.run_until_complete(task)
+ self.assertEqual(res, "ok")
+
def test_wait_for_waits_for_task_cancellation(self):
loop = asyncio.new_event_loop()
self.addCleanup(loop.close)