Python 在没有装饰器的情况下使用韧性重试

Question

我正在尝试使用 tenacity（没有装饰器）重试。我的代码看起来像解释的那样 here.

import logging
from tenacity import retry
import tenacity


def print_msg():
    try:
        logging.info('Hello')
        logging.info("World")
        raise Exception('Test error')
    except Exception as e:
        logging.error('caught error')
        raise e


if __name__ == '__main__':
    logging.basicConfig(
        format='%(asctime)s,%(msecs)d %(levelname)-8s [%(filename)s:%(lineno)d] %(message)s',
        datefmt='%d-%m-%Y:%H:%M:%S',
        level=logging.INFO)
    logging.info('Starting')
    try:
        r = tenacity.Retrying(
            tenacity.stop_after_attempt(2),
            tenacity.wait_incrementing(start=10, increment=100, max=1000),
            reraise=True
        )
        try:
            r.call(print_msg)
        except Exception:
            logging.error('Test error 2')
    except Exception:
        logging.error('Received Exception')

在执行上面的代码时。输出如下所示，没有重试

/Users/dmanna/PycharmProjects/demo/venv/bin/python /Users/dmanna/PycharmProjects/demo/retrier.py
25-11-2018:00:29:47,140 INFO     [retrier.py:21] Starting
25-11-2018:00:29:47,140 INFO     [retrier.py:8] Hello
25-11-2018:00:29:47,140 INFO     [retrier.py:9] World
25-11-2018:00:29:47,140 ERROR    [retrier.py:12] caught error
25-11-2018:00:29:47,141 ERROR    [retrier.py:31] Test error 2

Process finished with exit code 0

有人可以告诉我出了什么问题吗，因为我在上面的代码中没有看到任何重试？

Answer 1

已回答 here。交叉发布答案

Hum I don't think you're using the API correctly here:

r = tenacity.Retrying(
            tenacity.stop_after_attempt(2),
            tenacity.wait_incrementing(start=10, increment=100, max=1000),
            reraise=True
        )

This translates to:

r = tenacity.Retrying(
            sleep=tenacity.stop_after_attempt(2),
            stop=tenacity.wait_incrementing(start=10, increment=100, max=1000),
            reraise=True
        )

Which is not going to do what you want.

You want:

r = tenacity.Retrying(
            stop=tenacity.stop_after_attempt(2),
            wait=tenacity.wait_incrementing(start=10, increment=100, max=1000),
            reraise=True
        )

Answer 2

注意 Python 3.4+ 用户（支持注释），要在 Tenacity 中明确强制重试，一般用例是用简单的 @retry 对其进行注释，然后引发特殊异常TryAgain。

@retry
def do_something():
    result = something_else()
    if result == 23:
       raise TryAgain

这种方法类似于Python 2.7 的答案也可以实现：

import tenacity

def do_something():
    result = something_else()
    if result == 23:
       raise TryAgain

r = tenacity.Retrying(
        stop=tenacity.stop_after_attempt(2),
        wait=tenacity.wait_incrementing(start=10, increment=100, max=1000)
    )
r.wraps(do_something)

有关详细信息，请参阅 API documentation on whether to retry or the source that defines annotations。

Python 在没有装饰器的情况下使用韧性重试

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