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[英]How do I call an async function with method run_in_executor in Python/Tornado?
[英]How to catch exceptions in a python run_in_executor method call
如何在run_in_executor调用的run_long_thing()函数中引发异常? 看起来它正在被吞噬。 我不需要阻塞代码中的函数结果。 它基本上是一个火灾和遗忘功能,但如果有任何问题,我仍需要捕捉异常......
import asyncio
import time
def fire_and_forget(task, *args, **kwargs):
loop = asyncio.get_event_loop()
if callable(task):
#if threadpoolworker is set to None,
#the max_workers will default to the number of processors on the machine, multiplied by 5
return loop.run_in_executor(None, task, *args, **kwargs)
else:
raise TypeError('Task must be a callable.')
async def run_long_thing(sleep):
print("Doing long thing... {:}".format(sleep))
time.sleep(sleep)
print("Done doing long thing. {:}".format(sleep))
raise Exception("sh*t happens")
def do_it():
print("Starting my main thing...")
print("Calling my long thing...")
for i in range(0,10,1):
try:
fire_and_forget(run_long_thing, i)
print(i)
print("Pom pi dom...")
time.sleep(0.1)
print("POOOOM Pom pi dom...")
except:
print("can i see the sh*t?")
do_it()
首先,如果你调用time.sleep
你永远不会结束运行asyncio
事件循环所以没有结果检测到。 而不是调用time.sleep
在do_it
你最好不要做这样的事情
asyncio.get_event_loop().run_until_complete(asyncio.sleep(0.1))
现在,run_in_executor的返回是一个未来。 如果您不介意编写异步def并在asyncio
循环上使用create_task
,您可以执行类似的操作
async def run_long_thing(thing, *args):
try: await asyncio.get_event_loop().run_in_executor(None, thing, *args)
except:
#do stuff
但是更符合您当前的代码,您可以附加异常回调
def callback(future):
if future.exception(): #your long thing had an exception
# do something with future.exception()
那么当你调用run_in_executor时:
future = asyncio.get_event_loop().run_in_executor(None, fun, *args)
future.add_done_callback(callback)
然后,只要执行程序任务完成,就会调用callback
。 future.result()
将包含结果,如果它不是一个例外, future.exception()
将返回任何引发的异常
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