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python - 无法使用上下文管理器从线程中捕获异常

问题描述

目标脚本


from threading import Thread
import instrument
import sys

args=None
def main():
    function1()


def function1():
     with open("help11.txt") as f:
          print(f.read())

if __name__ == "__main__":
    with instrument.FooManager():
        t= Thread(target=main)
        t.start()
        t.join()

上下文管理器定义 Instrument.py

class FooManager(object):

    def __init__(self, **kwargs):
         self.kwargs = kwargs

    def __enter__(self):
        self.start_time, self.fmt_start_time = self.__timings()

    def __exit__(self, exc_type, exc_value, traceback):
        print(exc_type)
        print(exc_value)
        self.end_time, self.fmt_end_time = self.__timings()
        duration = (self.end_time - self.start_time)
        print("start_time",self.start_time)
        print("end_time",self.end_time)
        print("duration",duration)

    def __timings(self):

       return time.time(),time.strftime('%Y-%m-%d %H:%M %Z', time.gmtime(time.time()))

实际输出

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python3.6/threading.py", line 916, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.6/threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "test.py", line 10, in main
    function1(10000000, 1)
  File "test.py", line 14, in function1
    with open("help11.txt") as f:
FileNotFoundError: [Errno 2] No such file or directory: 'help11.txt'

None
None
fmt_start_time 1602782848.645685
end_time 1602782848.6461706
duration 0.0004856586456298828

预期产出

我想要的只是使用上下文管理器以某种方式捕获错误，而不是在 exc_type 和 exc_value 中将值设为 None 或者在上下文管理器中捕获线程引发的错误的推荐方法是什么

注意：当“with 语句”之后没有线程声明时，此代码可以正常工作

标签： pythonmultithreadingexceptioncontextmanager

解决方案

要从线程传播异常，请使用ThreadPoolExecutorfromconcurrent.futures

from concurrent.futures.thread import ThreadPoolExecutor


def foo():
    raise RuntimeError()


with ThreadPoolExecutor(max_workers=1) as executor:
    future = executor.submit(foo)
    print(future.result())

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