New submission from Michel Desmoulin:
If you trigger KeyboardInterrupt in a coroutine and catch it, the program
terminates cleanly:
import asyncio
async def bar():
raise KeyboardInterrupt
loop = asyncio.get_event_loop()
try:
loop.run_until_complete(bar())
except KeyboardInterrupt:
print("It's ok")
finally:
loop.stop()
loop.close()
This outputs:
It's ok
However, if you wrap the coroutine in a Task, you will get a mixed behavior:
try:
task = asyncio.ensure_future(bar())
loop.run_until_complete(task)
except KeyboardInterrupt:
print("It's ok")
This outputs:
It's ok
Task exception was never retrieved
future: <Task finished coro=<bar() done, defined at ki_bug.py:4>
exception=KeyboardInterrupt()>
Traceback (most recent call last):
File "ki_bug.py", line 10, in <module>
loop.run_until_complete(main_future)
File "/usr/lib/python3.5/asyncio/base_events.py", line 325, in
run_until_complete
self.run_forever()
File "/usr/lib/python3.5/asyncio/base_events.py", line 295, in run_forever
self._run_once()
File "/usr/lib/python3.5/asyncio/base_events.py", line 1258, in _run_once
handle._run()
File "/usr/lib/python3.5/asyncio/events.py", line 125, in _run
self._callback(*self._args)
File "/usr/lib/python3.5/asyncio/tasks.py", line 239, in _step
result = coro.send(None)
File "ki_bug.py", line 5, in bar
raise KeyboardInterrupt
KeyboardInterrupt
We have several contradictory behaviors: the KeyboardInterrupt is raised, and
captured by the future (since your can do task.exception() to suppress the
stracktrace) but also catched by except while the program is allowed to
continue, yet still the stack trace is displayed and eventually the program
return code will be 0.
It's very confusing.
----------
components: asyncio
messages: 260984
nosy: Michel Desmoulin, gvanrossum, haypo, yselivanov
priority: normal
severity: normal
status: open
title: Inconsistent behavior with KeyboardInterrupt and asyncio futures
type: behavior
versions: Python 3.5
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Python tracker <[email protected]>
<http://bugs.python.org/issue26455>
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