QUERY · ISSUE
uasyncio: Code throws exception under CPython
extmod
MicroPython allows a task to be created before issuing .run() but CPython throws an exception.
try:
import uasyncio as asyncio
except ImportError:
import asyncio
async def foo():
await asyncio.sleep(3)
async def bar():
await foo_task
foo_task = asyncio.create_task(foo()) # Naughty code here...
asyncio.run(bar())
Outcome under CPython 3.8.0:
adminpete@debian8:/mnt/qnap2/temp$ python3 -m rats_x
Traceback (most recent call last):
File "/usr/local/lib/python3.8/runpy.py", line 192, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/usr/local/lib/python3.8/runpy.py", line 85, in _run_code
exec(code, run_globals)
File "/mnt/qnap2/temp/rats_x.py", line 12, in <module>
foo_task = asyncio.create_task(foo())
File "/usr/local/lib/python3.8/asyncio/tasks.py", line 381, in create_task
loop = events.get_running_loop()
RuntimeError: no running event loop
sys:1: RuntimeWarning: coroutine 'foo' was never awaited
My view is that this doesn't matter, but I thought it worth reporting.
CANDIDATE · ISSUE
extmod/uasyncio gather return_exceptions=True does not return exceptions
extmod
This script works as expected under CPython but not under MicroPython:
try:
import uasyncio as asyncio
except ImportError:
import asyncio
async def barking(n):
print('Start barking')
for _ in range(6):
await asyncio.sleep(1)
print('Done barking.')
return 2 * n
async def foo(n):
print('Start timeout coro foo()')
while True:
await asyncio.sleep(1)
n += 1
return n
async def bar(n):
print('Start cancellable bar()')
while True:
await asyncio.sleep(1)
n += 1
return n
async def do_cancel(task):
await asyncio.sleep(5)
print('About to cancel bar')
task.cancel()
async def main():
tasks = [asyncio.create_task(bar(70))]
tasks.append(barking(21))
tasks.append(asyncio.wait_for(foo(10), 7))
asyncio.create_task(do_cancel(tasks[0]))
res = None
try:
res = await asyncio.gather(*tasks, return_exceptions=True)
except asyncio.TimeoutError:
print('Timeout')
except asyncio.CancelledError:
print('Cancelled')
print('Result: ', res)
asyncio.run(main())
Under CPython:
Start cancellable bar()
Start barking
Start timeout coro foo()
About to cancel bar
Done barking.
Result: [CancelledError(), 42, TimeoutError()]
MicroPython:
Start cancellable bar()
Start barking
Start timeout coro foo()
About to cancel bar
Cancelled
Result: None
The cancelled exception has propagated to the caller and the timeout exception has apparently vanished.