I picked this up in my unit tests which are admittedly testing some edge cases. When trying to use the loop to register a signal handler for SIGKILL (which itself is invalid) asyncio and uvloop behave differently.
A simple test that demonstrates the difference is this:
import asyncio
import signal
# import uvloop
# asyncio.DefaultEventLoopPolicy = uvloop.EventLoopPolicy
# asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
def my_sig_handler():
pass
loop = asyncio.get_event_loop()
loop.add_signal_handler(signal.SIGKILL, my_sig_handler)
loop.stop()
loop.close()
Running the script as is produces the asyncio output:
$ python3.5 uvloop-sig-test.py
Traceback (most recent call last):
File "/usr/local/lib/python3.5/asyncio/unix_events.py", line 95, in add_signal_handler
signal.signal(sig, _sighandler_noop)
File "/usr/local/lib/python3.5/signal.py", line 47, in signal
handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))
OSError: [Errno 22] Invalid argument
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "uvloop-sig-test.py", line 31, in <module>
loop.add_signal_handler(signal.SIGKILL, my_sig_handler)
File "/usr/local/lib/python3.5/asyncio/unix_events.py", line 108, in add_signal_handler
raise RuntimeError('sig {} cannot be caught'.format(sig))
RuntimeError: sig 9 cannot be caught
By uncommenting the uvloop part and running the script will produce the uvloop output:
$ python3.5 uvloop-sig-test.py
Traceback (most recent call last):
File "uvloop-sig-test.py", line 31, in <module>
loop.add_signal_handler(signal.SIGKILL, my_sig_handler)
File "uvloop/loop.pyx", line 1632, in uvloop.loop.Loop.add_signal_handler (uvloop/loop.c:30442)
File "uvloop/handles/signal.pyx", line 52, in uvloop.loop.UVSignal.start (uvloop/loop.c:42667)
File "uvloop/handles/handle.pyx", line 145, in uvloop.loop.UVHandle._fatal_error (uvloop/loop.c:37619)
OSError: [Errno 22] Invalid argument
On the box that I ran this test on the Python version was 3.5.0 (not the latest 3.5.1) so the Python module line numbers may be a little out.
I actually think that uvloop does the right thing in reporting the first error. However it would appear that the asyncio developers observed that the error reported is not very informative and wrapped it with a more informative error report.
I picked this up in my unit tests which are admittedly testing some edge cases. When trying to use the loop to register a signal handler for SIGKILL (which itself is invalid)
asyncioanduvloopbehave differently.A simple test that demonstrates the difference is this:
Running the script as is produces the
asynciooutput:By uncommenting the uvloop part and running the script will produce the uvloop output:
On the box that I ran this test on the Python version was 3.5.0 (not the latest 3.5.1) so the Python module line numbers may be a little out.
I actually think that
uvloopdoes the right thing in reporting the first error. However it would appear that theasynciodevelopers observed that the error reported is not very informative and wrapped it with a more informative error report.