我正在尝试创建一个 python 装饰器,它接受带有 args 和 kwargs 的函数,在新进程中执行它,关闭它并返回函数返回的任何内容,包括引发相同的异常(如果有)。
目前,如果函数没有引发异常,我的装饰器可以正常处理函数,但无法提供回溯。如何将其传回父进程?
from functools import wraps
from multiprocessing import Process, Queue
import sys
def process_wrapper(func):
@wraps(func)
def wrapper(*args, **kwargs):
# queue for communicating between parent and child processes
q = Queue()
def func_to_q(_q: Queue, *_args, **_kwargs):
# do the same as func, but put result into the queue. Also put
# there an exception if any.
try:
_res = func(*_args, **_kwargs)
_q.put(_res)
except:
_q.put(sys.exc_info())
# start another process and wait for it to join
p = Process(target=func_to_q, args=(q, )+args, kwargs=kwargs)
p.start()
p.join()
# get result from the queue and return it, or raise if it's an exception
res = q.get(False)
if isinstance(res, tuple) and isinstance(res[0], Exception):
raise res[1].with_traceback(res[2])
else:
return res
return wrapper
if __name__ == '__main__':
@process_wrapper
def ok():
return 'ok'
@process_wrapper
def trouble():
def inside():
raise UserWarning
inside()
print(ok())
print(trouble())
我期望结果是这样的:
ok
Traceback (most recent call last):
File "/temp.py", line 47, in <module>
print(trouble())
File "/temp.py", line 44, in trouble
inside()
File "/temp.py", line 43, in inside
raise UserWarning
UserWarning
Process finished with exit code 1
但子进程似乎无法将堆栈跟踪放入队列中,我得到以下信息:
ok
Traceback (most recent call last):
File "/temp.py", line 47, in <module>
print(trouble())
File "/temp.py", line 26, in wrapper
res = q.get(False)
File "/usr/lib/python3.6/multiprocessing/queues.py", line 107, in get
raise Empty
queue.Empty
Process finished with exit code 1
另外,如果子进程仅将异常本身放入队列_q.put(sys.exc_info()[1])
,父级从那里获取它并引发,但使用新的堆栈跟踪(注意缺少对inside()
):
ok
Traceback (most recent call last):
File "/temp.py", line 47, in <module>
print(trouble())
File "/temp.py", line 28, in wrapper
raise res
UserWarning
Process finished with exit code 1