这是一个棘手的小问题，我想提出我的解决方案。我发现了一些其他的解决方案(异步。例如IO)看起来很有前途，但也呈现出一些黑盒子。队列/事件循环方法将您与某个实现联系在一起。然而，并发期货的源代码只有大约1000行，很容易理解。它让我很容易地解决了我的问题:创建临时的工作线程，而不需要太多的设置，并且能够在主线程中捕获异常。

我的解决方案使用并发期货API和线程API。它允许你创建一个worker，给你线程和未来。这样，你就可以加入线程来等待结果:

worker = Worker(test)
thread = worker.start()
thread.join()
print(worker.future.result())

.．.或者你可以让worker在完成时发送一个回调:

worker = Worker(test)
thread = worker.start(lambda x: print('callback', x))

.．.或者你可以循环直到事件完成:

worker = Worker(test)
thread = worker.start()

while True:
    print("waiting")
    if worker.future.done():
        exc = worker.future.exception()
        print('exception?', exc)
        result = worker.future.result()
        print('result', result)           
        break
    time.sleep(0.25)

代码如下:

from concurrent.futures import Future
import threading
import time

class Worker(object):
    def __init__(self, fn, args=()):
        self.future = Future()
        self._fn = fn
        self._args = args

    def start(self, cb=None):
        self._cb = cb
        self.future.set_running_or_notify_cancel()
        thread = threading.Thread(target=self.run, args=())
        thread.daemon = True #this will continue thread execution after the main thread runs out of code - you can still ctrl + c or kill the process
        thread.start()
        return thread

    def run(self):
        try:
            self.future.set_result(self._fn(*self._args))
        except BaseException as e:
            self.future.set_exception(e)

        if(self._cb):
            self._cb(self.future.result())

.．.和测试函数:

def test(*args):
    print('args are', args)
    time.sleep(2)
    raise Exception('foo')

使用异常存储包装线程。

import threading
import sys
class ExcThread(threading.Thread):

    def __init__(self, target, args = None):
        self.args = args if args else []
        self.target = target
        self.exc = None
        threading.Thread.__init__(self)

    def run(self):
        try:
            self.target(*self.args)
            raise Exception('An error occured here.')
        except Exception:
            self.exc=sys.exc_info()

def main():
    def hello(name):
        print(!"Hello, {name}!")
    thread_obj = ExcThread(target=hello, args=("Jack"))
    thread_obj.start()

    thread_obj.join()
    exc = thread_obj.exc
    if exc:
        exc_type, exc_obj, exc_trace = exc
        print(exc_type, ':',exc_obj, ":", exc_trace)

main()

我喜欢这门课:

https://gist.github.com/earonesty/b88d60cb256b71443e42c4f1d949163e

import threading
from typing import Any


class PropagatingThread(threading.Thread):
    """A Threading Class that raises errors it caught, and returns the return value of the target on join."""

    def __init__(self, *args, **kwargs):
        self._target = None
        self._args = ()
        self._kwargs = {}
        super().__init__(*args, **kwargs)
        self.exception = None
        self.return_value = None
        assert self._target

    def run(self):
        """Don't override this if you want the behavior of this class, use target instead."""
        try:
            if self._target:
                self.return_value = self._target(*self._args, **self._kwargs)
        except Exception as e:
            self.exception = e
        finally:
            # see super().run() for why this is necessary
            del self._target, self._args, self._kwargs

    def join(self, timeout=None) -> Any:
        super().join(timeout)
        if self.exception:
            raise self.exception
        return self.return_value

Pygolang提供同步功能。工作组，特别是将异常从派生的工作线程传播到主线程。例如:

#!/usr/bin/env python
"""This program demostrates how with sync.WorkGroup an exception raised in
spawned thread is propagated into main thread which spawned the worker."""

from __future__ import print_function
from golang import sync, context

def T1(ctx, *argv):
    print('T1: run ... %r' % (argv,))
    raise RuntimeError('T1: problem')

def T2(ctx):
    print('T2: ran ok')

def main():
    wg = sync.WorkGroup(context.background())
    wg.go(T1, [1,2,3])
    wg.go(T2)

    try:
        wg.wait()
    except Exception as e:
        print('Tmain: caught exception: %r\n' %e)
        # reraising to see full traceback
        raise

if __name__ == '__main__':
    main()

在运行时给出以下结果:

T1: run ... ([1, 2, 3],)
T2: ran ok
Tmain: caught exception: RuntimeError('T1: problem',)

Traceback (most recent call last):
  File "./x.py", line 28, in <module>
    main()
  File "./x.py", line 21, in main
    wg.wait()
  File "golang/_sync.pyx", line 198, in golang._sync.PyWorkGroup.wait
    pyerr_reraise(pyerr)
  File "golang/_sync.pyx", line 178, in golang._sync.PyWorkGroup.go.pyrunf
    f(pywg._pyctx, *argv, **kw)
  File "./x.py", line 10, in T1
    raise RuntimeError('T1: problem')
RuntimeError: T1: problem

问题的原始代码将是:

    wg = sync.WorkGroup(context.background())

    def _(ctx):
        shul.copytree(sourceFolder, destFolder)
    wg.go(_)

    # waits for spawned worker to complete and, on error, reraises
    # its exception on the main thread.
    wg.wait()

类似于RickardSjogren的方法，没有Queue, sys等，但也没有一些信号监听器:直接执行一个异常处理程序，对应于一个异常块。

#!/usr/bin/env python3

import threading

class ExceptionThread(threading.Thread):

    def __init__(self, callback=None, *args, **kwargs):
        """
        Redirect exceptions of thread to an exception handler.

        :param callback: function to handle occured exception
        :type callback: function(thread, exception)
        :param args: arguments for threading.Thread()
        :type args: tuple
        :param kwargs: keyword arguments for threading.Thread()
        :type kwargs: dict
        """
        self._callback = callback
        super().__init__(*args, **kwargs)

    def run(self):
        try:
            if self._target:
                self._target(*self._args, **self._kwargs)
        except BaseException as e:
            if self._callback is None:
                raise e
            else:
                self._callback(self, e)
        finally:
            # Avoid a refcycle if the thread is running a function with
            # an argument that has a member that points to the thread.
            del self._target, self._args, self._kwargs, self._callback

只有自我。_callback和run()中的except块是普通threading.Thread之外的。

这个问题有很多非常奇怪复杂的答案。我是不是把它简化了，因为对我来说，这似乎对大多数事情都足够了。

from threading import Thread

class PropagatingThread(Thread):
    def run(self):
        self.exc = None
        try:
            if hasattr(self, '_Thread__target'):
                # Thread uses name mangling prior to Python 3.
                self.ret = self._Thread__target(*self._Thread__args, **self._Thread__kwargs)
            else:
                self.ret = self._target(*self._args, **self._kwargs)
        except BaseException as e:
            self.exc = e

    def join(self, timeout=None):
        super(PropagatingThread, self).join(timeout)
        if self.exc:
            raise self.exc
        return self.ret

如果你确定你只会在一个或另一个版本的Python上运行，你可以将run()方法减少到只有被破坏的版本(如果你只在3之前的Python版本上运行)，或者仅仅是干净的版本(如果你只在3开始的Python版本上运行)。

使用示例:

def f(*args, **kwargs):
    print(args)
    print(kwargs)
    raise Exception('I suck at this')

t = PropagatingThread(target=f, args=(5,), kwargs={'hello':'world'})
t.start()
t.join()

当您加入时，您将看到在另一个线程上引发异常。

如果您正在使用six或仅在Python 3上使用，则可以改进重新引发异常时获得的堆栈跟踪信息。您可以将内部异常包装在一个新的外部异常中，而不是仅在连接点处使用堆栈，并使用

six.raise_from(RuntimeError('Exception in thread'),self.exc)

or

raise RuntimeError('Exception in thread') from self.exc