python代码出现异常，自动重新运行

demo如下：

from retrying import retry

def retry_error(exception):
    return isinstance(exception, NameError)
    # return isinstance(exception, Exception)


@retry(retry_on_exception=retry_error, stop_max_attempt_number=3)
def demo_():
    print('重试')
    print(a)


if __name__ == '__main__':
    demo_()

　　

运行如图：

 定义了一个demo_函数，里面打印的变量a，没有被赋值，会导致报“NameError: name 'a' is not defined”错误，但是观察上述截图，发现代码运行了3次以后才抛出异常。这就借用了retrying里面的失败重试机制，定义了retry_error函数去捕获NameError异常，其实也可以偷懒直接去捕获Exception。用retry_on_result去传入一个函数对象，stop_max_attempt_number控制次数。

以上参考博客：https://www.cnblogs.com/du-jun/p/12256281.html

自己实现了一个失败重试装饰器的demo：

# def retry(**kw):
#     def wrapper(func):
#         def _wrapper(*args, **kwargs):
#             raise_ex = 0
#             for _ in range(kw['retry_num']):
#                 print(f"第{_}次操作")
#                 try:
#                     return func(*args, **kwargs)
#                 except Exception as e:
#                     raise_ex += 1
#                     if raise_ex == kw['retry_num']:
#                         raise e
#
#         return _wrapper
#
#     return wrapper
#
#
# @retry(retry_num=3)
# def demo():
#     print('a')
#     print(a)
#     # raise NameError
#
#
# if __name__ == '__main__':
#     demo()


def retry(loop_num=2):
    def wrapper(func):
        def _wrapper(*args, **kwargs):
            raise_ex = 0
            for _ in range(loop_num):
                print(f"第{_}次操作")
                try:
                    return func(*args, **kwargs)
                except Exception as e:
                    raise_ex += 1
                    if raise_ex == loop_num:
                        raise e

        return _wrapper

    return wrapper


@retry(loop_num=3)
def demo():
    print('a')
    print(a)
    # raise NameError


if __name__ == '__main__':
    demo()

效果如图：

 增加等待时间：

import time


def retry(loop_num=2, wait_time=1):
    """
    :param loop_num: 循环次数，默认2次
    :param wait_time: 等待时间，默认1s
    :return:
    """
    def wrapper(func):
        def _wrapper(*args, **kwargs):
            raise_ex = 0
            for i in range(1, loop_num + 1):
                print(f"第{i}次操作")
                try:
                    func(*args, **kwargs)
                except Exception as e:
                    time.sleep(wait_time)
                    raise_ex += 1
                    if raise_ex == loop_num:
                        raise e

        return _wrapper

    return wrapper


@retry()
def demo_():
    print('开始重试')
    print(a)


if __name__ == '__main__':
    demo_()