open_process() sometimes "swallows" exceptions #1844
Description
I had an error in my code:
import trio
async def run():
async with await trio.open_process('python3 -c "while True: pass"', shell=True):
print('before')
1 + ''
print('after')
trio.run(run)Running the above felt as if the program just hangs:
$ .venv/bin/python3 swallowed-error.py
beforeIf I press Ctrl-C, I finally get my TypeError printed out. It looks as if it was buffered before:
$ .venv/bin/python3 swallowed-error.py
before
^CTraceback (most recent call last):
File "<string>", line 1, in <module>
KeyboardInterrupt
Traceback (most recent call last):
File "/home/user/src/swallowed-error.py", line 6, in run
1 + ''
TypeError: unsupported operand type(s) for +: 'int' and 'str'
During handling of the above exception, another exception occurred:
...(Of course, I haven't noticed TypeError at first, because the interesting part comes before deep KeyboardInterrupt traceback.)
I would expect Trio not to hide exceptions from me :-)
Trio 0.17.0, MacOS 10.14.6, Python 3.9.0.
Full output, seems to block on `await wait_child_exiting()`
$ .venv/bin/python3 swallowed-error.py
before
^CTraceback (most recent call last):
File "<string>", line 1, in <module>
KeyboardInterrupt
Traceback (most recent call last):
File "/home/user/src/swallowed-error.py", line 6, in run
1 + ''
TypeError: unsupported operand type(s) for +: 'int' and 'str'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/user/src/swallowed-error.py", line 9, in <module>
trio.run(run)
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_core/_run.py", line 1928, in run
raise runner.main_task_outcome.error
File "/home/user/src/swallowed-error.py", line 7, in run
print('after')
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_abc.py", line 261, in __aexit__
await self.aclose()
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_subprocess.py", line 198, in aclose
await self.wait()
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_subprocess.py", line 221, in wait
await wait_child_exiting(self)
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_subprocess_platform/kqueue.py", line 41, in wait_child_exiting
await _core.wait_kevent(process.pid, select.KQ_FILTER_PROC, abort)
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_core/_generated_io_kqueue.py", line 30, in wait_kevent
return await GLOBAL_RUN_CONTEXT.runner.io_manager.wait_kevent(ident, filter, abort_func)
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_core/_io_kqueue.py", line 132, in wait_kevent
return await _core.wait_task_rescheduled(abort)
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_core/_traps.py", line 166, in wait_task_rescheduled
return (await _async_yield(WaitTaskRescheduled(abort_func))).unwrap()
File "/home/user/src/.venv/lib/python3.9/site-packages/outcome/_impl.py", line 138, in unwrap
raise captured_error
File "/home/user/src/.venv/lib/python3.9/site-packages/trio/_core/_run.py", line 1178, in raise_cancel
raise KeyboardInterrupt
KeyboardInterrupt