Python随机跳过循环迭代

时间:2019-02-26 14:19:22

标签: python

在编写Python代码时,我是一个相对新手。这是我的问题,我正在重新启动服务器,需要验证服务是否已重新启动。服务器重新联机后,我将运行命令并将输出存储到txt。然后,我针对txt文档启动一个for循环,以确保该服务已启动。但是,有时会跳过for循环,而不会跳过其他循环。

def verify_serv():
    print ("start verif placeholder")#for troubleshooting 

    txtdoc = open('output2.txt','r')
    regexp = re.compile(r'\[STARTING\]')
    regexp2 = re.compile(r'\[STARTED\]')

    for line in txtdoc:
        match = regexp.match(line)
        nomatch = regexp2.match(line)
        print('in for loop')#for troubleshooting 
        if match:
            print ('in if loop')#for troubleshooting 
            print ('Still Starting \n\n\n\n\n\n')# testing only
            time.sleep(5)
            break
        elif nomatch:
            print('Done')
            end_email()


    txtdoc.close()     
    os.remove('output2.txt')

    print('end loop')#for troubleshooting 
    match = None
    nomatch = None
    txtdoc = None
    time.sleep(60)
    command_2()# pull new output file to recheck

我还将添加一些输出。

admin:#This iteration Skips Loop
starting verification
start verif placeholder
end loop

starting verification# This iteration enters loop
start verif placeholder
in for loop #x91
in if loop
Still Starting 






end loop

admin: # loop Completes Services Restated
starting verification
start verif placeholder
in for loop #x80
Done

以上情况显示了正确的结果,但有时代码将仅运行而未完成。

任何帮助将不胜感激。

1 个答案:

答案 0 :(得分:0)

您在这里有一个“竞争条件”:如果在服务启动之前(甚至开始启动)打开文件 ,该文件将为空,因此for循环会停。您可以通过睡觉来获得正确的主意,但是您必须将其放入 second 循环中,因此您将重新打开该文件并再次检查它。像这样:

def verify_serv():
    # Infinite loop to keep checking the file
    while True:
        # The `with` block ensures the file will be closed automatically
        with open('output2.txt') as f:
            for line in f:
                if '[STARTED]' in line:
                    # It's started, so we're done
                    return

        # But if we got here, it hasn't started yet, so sleep and try again
        time.sleep(5)