python 超時重試方法

在應用中，有時候會依賴第三方模塊執行方法，比如調用某模塊的上傳下載，數據庫查詢等操作的時候，如果出現網絡問題或其他問題，可能有超時重新請求的情況；

目前的解決方案有

1. 信號量，但不支持window；

2.多線程，但是如果是大量的數據重復操作嘗試，會出現線程管理混亂，開啟上萬個線程的問題；

3.結合采用 eventlet 和 retrying模塊 (eventlet 原理尚需深入研究)

下面的方法實現：超過指定時間重新嘗試某個方法

 
                   # -*- coding: utf-8 -*- 
                  
                   import 
                   random 
                  
                   import 
                   time 
                  
                   import 
                   eventlet 
                  
                   from 
                   retrying  
                   import 
                   retry 
                  
                   eventlet.monkey_patch() 
                  
                   class 
                   RetryTimeOutException(Exception): 
                  
                   def 
                   __init__( 
                   self 
                   ,  
                   * 
                   args,  
                   * 
                   * 
                   kwargs): 
                  
                   pass 
                  
                   def 
                   retry_if_timeout(exception): 
                  
                   """Return True if we should retry (in this case when it's an IOError), False otherwise""" 
                  
                   return 
                   isinstance 
                   (exception, RetryTimeOutException) 
                  
                   def 
                   retry_fun(retries 
                   = 
                   3 
                   , timeout_second 
                   = 
                   2 
                   ): 
                  
                   """ 
                  
                   will retry ${retries} times when process time beyond ${timeout_second} ; 
                  
                   :param retries: The retry times 
                  
                   :param timeout_second: The max process time 
                  
                   """ 
                  
                   def 
                   retry_decor(func): 
                  
                   @retry 
                   (stop_max_attempt_number 
                   = 
                   retries, retry_on_exception 
                   = 
                   retry_if_timeout) 
                  
                   def 
                   decor( 
                   * 
                   args,  
                   * 
                   * 
                   kwargs): 
                  
                   print 
                   ( 
                   "In retry method.." 
                   ) 
                  
                   pass_flag  
                   = 
                   False 
                  
                   with eventlet.Timeout(timeout_second,  
                   False 
                   ): 
                  
                   r  
                   = 
                   func( 
                   * 
                   args,  
                   * 
                   * 
                   kwargs) 
                  
                   pass_flag  
                   = 
                   True 
                  
                   print 
                   ( 
                   "Success after method." 
                   ) 
                  
                   if 
                   not 
                   pass_flag: 
                  
                   raise 
                   RetryTimeOutException( 
                   "Time out.." 
                   ) 
                  
                   print 
                   ( 
                   "Exit from retry." 
                   ) 
                  
                   return 
                   r 
                  
                   return 
                   decor 
                  
                   return 
                   retry_decor 
                  
                   def 
                   do_request(): 
                  
                   print 
                   ( 
                   "begin request..." 
                   ) 
                  
                   sleep_time  
                   = 
                   random.randint( 
                   1 
                   ,  
                   4 
                   ) 
                  
                   print 
                   ( 
                   "request sleep time: %s." 
                   % 
                   sleep_time) 
                  
                   time.sleep(sleep_time) 
                  
                   print 
                   ( 
                   "end request..." 
                   ) 
                  
                   return 
                   True 
                  
                   @retry_fun 
                   (retries 
                   = 
                   3 
                   ) 
                  
                   def 
                   retry_request(): 
                  
                   r  
                   = 
                   do_request() 
                  
                   print 
                   (r) 
                  
                   if 
                   __name__  
                   = 
                   = 
                   '__main__' 
                   : 
                  
                   retry_request()