Question

以下不起作用。我有一个程序连接到一个网页，但有时由于一些问题，它无法连接我希望程序完全重新启动错误全部由它自己。想象一下main函数调用程序，我该如何编写这样的代码？

import numpy as np

def main():
    np.load('File.csv')

for i in range(1, 10):
    try:
        main()
    except Exception as e:
        print e
        print 'Restarting!'
        main()

Answer 1

对于这样的事情（连接到网页），通常最好根据时间而不是尝试连接的次数来设置上限。因此，请改用while循环：

import numpy as np
import time

def main():
    np.load('file.csv')

start = time.time()
stop = start + 5
attempts = 0
result = 'failed'

while True:
    if time.time()<stop:
        try:
            main()
        except Exception as e:
            attempts += 1
            print e
            time.sleep(0.1) # optional
            print 'Restarting!'
            continue
        else:
            result = 'succeeded'
    print 'Connection %s after %i attempts.' % (result, attempts)
    break

可选：每次尝试失败后，我都会暂停100毫秒。这有助于建立连接。

然后将整个事情包装在一个函数中，以后可以用于其他项目：

# retry.py

import time

def retry(f, seconds, pause = 0):
    start = time.time()
    stop = start + seconds
    attempts = 0
    result = 'failed'

    while True:
        if time.time()<stop:
            try:
                f()
            except Exception as e:
                attempts += 1
                print e
                time.sleep(pause)
                print 'Restarting!'
                continue
            else:
                result = 'succeeded'
        print '%s after %i attempts.' % (result, attempts)
        break

现在就这样做：

import numpy as np
from retry import retry

def main():
    np.load('file.csv')

retry(main, 5, 0.1)

测试程序：

class RetryTest():
    def __init__(self, succeed_on = 0, excp = Exception()):
        self.succeed_on = succeed_on
        self.attempts = 0
        self.excp = excp
    def __call__(self):
        self.attempts += 1
        if self.succeed_on == self.attempts:
            self.attempts = 0
        else:
            raise self.excp

retry_test1 = RetryTest(3)
retry(retry_test1, 5, 0.1)
# succeeded after 3 attempts.
retry_test2 = RetryTest()
retry(retry_test2, 5, 0.1)
# failed after 50 attempts.

Answer 2

你可以在这里使用递归函数自动重启你的代码。使用setrecursionlimit（）来定义尝试次数，如下所示：

import numpy as np
import sys
sys.setrecursionlimit(10)  # set recursion depth limit


def main():
    try:
        a = np.load('file.csv')
        if a:
            return a
    except Exception as e:
        return main()

result = main()
print result

希望这有助于：）

退出错误后如何自动重启我的python代码？

2 个答案: