我怎么调用函数或者我怎么包装它，如果它超过5秒脚本取消它?

我发布了一个要点，用装饰器和threading.Timer解决了这个问题。下面是它的分类。

导入和设置兼容性

它是用Python 2和3测试的。它也应该在Unix/Linux和Windows下工作。

首先是进口。这些尝试保持代码的一致性，而不管Python版本:

from __future__ import print_function
import sys
import threading
from time import sleep
try:
    import thread
except ImportError:
    import _thread as thread

使用版本独立代码:

try:
    range, _print = xrange, print
    def print(*args, **kwargs): 
        flush = kwargs.pop('flush', False)
        _print(*args, **kwargs)
        if flush:
            kwargs.get('file', sys.stdout).flush()            
except NameError:
    pass

现在我们已经从标准库导入了我们的功能。

exit_after装饰

接下来，我们需要一个函数来终止子线程的main():

def quit_function(fn_name):
    # print to stderr, unbuffered in Python 2.
    print('{0} took too long'.format(fn_name), file=sys.stderr)
    sys.stderr.flush() # Python 3 stderr is likely buffered.
    thread.interrupt_main() # raises KeyboardInterrupt

这是decorator本身:

def exit_after(s):
    '''
    use as decorator to exit process if 
    function takes longer than s seconds
    '''
    def outer(fn):
        def inner(*args, **kwargs):
            timer = threading.Timer(s, quit_function, args=[fn.__name__])
            timer.start()
            try:
                result = fn(*args, **kwargs)
            finally:
                timer.cancel()
            return result
        return inner
    return outer

使用

下面这个用法直接回答了你关于5秒后退出的问题!：

@exit_after(5)
def countdown(n):
    print('countdown started', flush=True)
    for i in range(n, -1, -1):
        print(i, end=', ', flush=True)
        sleep(1)
    print('countdown finished')

演示:

>>> countdown(3)
countdown started
3, 2, 1, 0, countdown finished
>>> countdown(10)
countdown started
10, 9, 8, 7, 6, countdown took too long
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 11, in inner
  File "<stdin>", line 6, in countdown
KeyboardInterrupt

第二个函数调用将不会结束，相反，进程应该退出并返回一个跟踪!

KeyboardInterrupt并不总是停止一个睡眠线程

注意，在Windows上的Python 2中，睡眠并不总是被键盘中断中断，例如:

@exit_after(1)
def sleep10():
    sleep(10)
    print('slept 10 seconds')

>>> sleep10()
sleep10 took too long         # Note that it hangs here about 9 more seconds
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 11, in inner
  File "<stdin>", line 3, in sleep10
KeyboardInterrupt

它也不可能中断扩展中运行的代码，除非它显式地检查PyErr_CheckSignals()，参见忽略Cython, Python和KeyboardInterrupt

在任何情况下，我都会避免让线程休眠超过一秒钟——这在处理器时间上是一eon。

我怎么调用这个函数或者我把它包装在什么里面，这样如果它花费超过5秒脚本就会取消它并做其他事情?

要捕获它并做其他事情，你可以捕获KeyboardInterrupt。

>>> try:
...     countdown(10)
... except KeyboardInterrupt:
...     print('do something else')
... 
countdown started
10, 9, 8, 7, 6, countdown took too long
do something else

我有一个不同的建议，这是一个纯函数(与线程建议相同的API)，似乎工作得很好(基于这个线程的建议)

def timeout(func, args=(), kwargs={}, timeout_duration=1, default=None):
    import signal

    class TimeoutError(Exception):
        pass

    def handler(signum, frame):
        raise TimeoutError()

    # set the timeout handler
    signal.signal(signal.SIGALRM, handler) 
    signal.alarm(timeout_duration)
    try:
        result = func(*args, **kwargs)
    except TimeoutError as exc:
        result = default
    finally:
        signal.alarm(0)

    return result

超时装饰器不能在Windows系统上工作，因为Windows不太支持信号。

如果你在windows系统中使用超时装饰器，你会得到以下结果

AttributeError: module 'signal' has no attribute 'SIGALRM'

有些人建议使用use_signals=False，但对我没用。

作者@bitranox创建了以下包:

pip install https://github.com/bitranox/wrapt-timeout-decorator/archive/master.zip

代码示例:

import time
from wrapt_timeout_decorator import *

@timeout(5)
def mytest(message):
    print(message)
    for i in range(1,10):
        time.sleep(1)
        print('{} seconds have passed'.format(i))

def main():
    mytest('starting')


if __name__ == '__main__':
    main()

给出以下例外:

TimeoutError: Function mytest timed out after 5 seconds

有很多建议，但没有一个是使用并发的。期货，我认为这是最清晰的处理方式。

from concurrent.futures import ProcessPoolExecutor

# Warning: this does not terminate function if timeout
def timeout_five(fnc, *args, **kwargs):
    with ProcessPoolExecutor() as p:
        f = p.submit(fnc, *args, **kwargs)
        return f.result(timeout=5)

超级简单的阅读和维护。

我们创建一个池，提交一个进程，然后等待5秒，然后引发一个TimeoutError，你可以根据需要捕获和处理它。

本机为python 3.2+，并反向移植到2.7 (pip install futures)。

线程和进程之间的切换非常简单，只需将ProcessPoolExecutor替换为ThreadPoolExecutor。

如果您想在超时时终止进程，我建议您查看Pebble。

以防对任何人都有帮助，在@piro的回答的基础上，我做了一个函数装饰器:

import time
import signal
from functools import wraps


def timeout(timeout_secs: int):
    def wrapper(func):
        @wraps(func)
        def time_limited(*args, **kwargs):
            # Register an handler for the timeout
            def handler(signum, frame):
                raise Exception(f"Timeout for function '{func.__name__}'")

            # Register the signal function handler
            signal.signal(signal.SIGALRM, handler)

            # Define a timeout for your function
            signal.alarm(timeout_secs)

            result = None
            try:
                result = func(*args, **kwargs)
            except Exception as exc:
                raise exc
            finally:
                # disable the signal alarm
                signal.alarm(0)

            return result

        return time_limited

    return wrapper

在一个有20秒超时的函数上使用包装器看起来像这样:

    @timeout(20)
    def my_slow_or_never_ending_function(name):
        while True:
            time.sleep(1)
            print(f"Yet another second passed {name}...")

    try:
        results = my_slow_or_never_ending_function("Yooo!")
    except Exception as e:
        print(f"ERROR: {e}")

突出了

引发TimeoutError使用异常在超时时发出警报-可以很容易地修改 跨平台:Windows和Mac OS X 兼容性:Python 3.6+(我也在Python 2.7上进行了测试，它可以在很小的语法调整下工作)

有关平行地图的完整解释和扩展，请参见https://flipdazed.github.io/blog/quant%20dev/parallel-functions-with-timeouts

最小的例子

>>> @killer_call(timeout=4)
... def bar(x):
...        import time
...        time.sleep(x)
...        return x
>>> bar(10)
Traceback (most recent call last):
  ...
__main__.TimeoutError: function 'bar' timed out after 4s

正如预期的那样

>>> bar(2)
2

完整代码

import multiprocessing as mp
import multiprocessing.queues as mpq
import functools
import dill

from typing import Tuple, Callable, Dict, Optional, Iterable, List, Any

class TimeoutError(Exception):

    def __init__(self, func: Callable, timeout: int):
        self.t = timeout
        self.fname = func.__name__

    def __str__(self):
            return f"function '{self.fname}' timed out after {self.t}s"


def _lemmiwinks(func: Callable, args: Tuple, kwargs: Dict[str, Any], q: mp.Queue):
    """lemmiwinks crawls into the unknown"""
    q.put(dill.loads(func)(*args, **kwargs))


def killer_call(func: Callable = None, timeout: int = 10) -> Callable:
    """
    Single function call with a timeout

    Args:
        func: the function
        timeout: The timeout in seconds
    """

    if not isinstance(timeout, int):
        raise ValueError(f'timeout needs to be an int. Got: {timeout}')

    if func is None:
        return functools.partial(killer_call, timeout=timeout)

    @functools.wraps(killer_call)
    def _inners(*args, **kwargs) -> Any:
        q_worker = mp.Queue()
        proc = mp.Process(target=_lemmiwinks, args=(dill.dumps(func), args, kwargs, q_worker))
        proc.start()
        try:
            return q_worker.get(timeout=timeout)
        except mpq.Empty:
            raise TimeoutError(func, timeout)
        finally:
            try:
                proc.terminate()
            except:
                pass
    return _inners

if __name__ == '__main__':
    @killer_call(timeout=4)
    def bar(x):
        import time
        time.sleep(x)
        return x

    print(bar(2))
    bar(10)

笔记

由于dill的工作方式，您需要在函数内部导入。

这也意味着如果目标函数中有导入，这些函数可能与doctest不兼容。你将会遇到__import__未找到的问题。