How to catch exceptions in a python run_in_executor method call

first of all, if you call time.sleep you'll never end up running the asyncio event loop so no results will get detected. instead of calling time.sleep in do_it you're better off doing something like

asyncio.get_event_loop().run_until_complete(asyncio.sleep(0.1))

Now, the return from run_in_executor is a future. If you don't mind writing an async def and using create_task on your asyncio loop you could do something like

async def run_long_thing(thing, *args):    try: await asyncio.get_event_loop().run_in_executor(None, thing, *args)    except:        #do stuff

But more in line with your current code you can attach an exception callback

def callback(future):if future.exception(): #your long thing had an exception        # do something with future.exception()

then when you call run_in_executor:

future = asyncio.get_event_loop().run_in_executor(None, fun, *args)future.add_done_callback(callback)

Then callback will be called whenever your executor task completes. future.result() will contain the result if it is no an exception, and future.exception() will give you back any raised exception