python 类变量在多线程下的共享与释放问题-Tutoriel Python-php.cn

python 类变量在多线程下的共享与释放问题

高洛峰

Libérer： 2016-10-18 10:32:20

original

1239 Les gens l'ont consulté

最近被多线程给坑了下，没意识到类变量在多线程下是共享的，还有一个就是没意识到内存释放问题，导致越累越大

1.python 类变量在多线程情况下的是共享的

2.python 类变量在多线程情况下的释放是不完全的

3.python 类变量在多线程情况下没释放的那部分内存是可以重复利用的

import threading
 import time
   
 class Test:
   
     cache = {}
       
     @classmethod
     def get_value(self, key):
         value = Test.cache.get(key, [])
         return len(value)
   
     @classmethod
     def store_value(self, key, value):
         if not Test.cache.has_key(key):
             Test.cache[key] = range(value)
         else:
             Test.cache[key].extend(range(value))
         return len(Test.cache[key])
   
     @classmethod
     def release_value(self, key):
         if Test.cache.has_key(key):
             Test.cache.pop(key)
         return True
   
     @classmethod
     def print_cache(self):
         print &#39;print_cache:&#39;
         for key in Test.cache:
             print &#39;key: %d, value:%d&#39; % (key, len(Test.cache[key]))
   
 def worker(number, value):
     key = number % 5
     print &#39;threading: %d, store_value: %d&#39; % (number, Test.store_value(key, value))
     time.sleep(10)
     print &#39;threading: %d, release_value: %s&#39; % (number, Test.release_value(key))
   
 if __name__ == &#39;__main__&#39;:
     thread_num = 10
       
     thread_pool = []
     for i in range(thread_num):
         th = threading.Thread(target=worker,args=[i, 1000000])
         thread_pool.append(th)
         thread_pool[i].start()
   
     for thread in thread_pool:
         threading.Thread.join(thread)
       
     Test.print_cache()
     time.sleep(10)
       
     thread_pool = []
     for i in range(thread_num):
         th = threading.Thread(target=worker,args=[i, 100000])
         thread_pool.append(th)
         thread_pool[i].start()
   
     for thread in thread_pool:
         threading.Thread.join(thread)
       
     Test.print_cache()
     time.sleep(10)

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公用的数据，除非是只读的，不然不要当类成员变量，一是会共享，二是不好释放。