python类变量在多线程下的共享与释放问题[python高级教程]

Z时代
2024-01-10
分类：综合

python 类变量在多线程下的共享与释放问题[python高级教程]

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 "print_cache:"
         for key in Test.cache:
             print "key: %d, value:%d" % (key, len(Test.cache[key]))
 def worker(number, value):
     key = number % 5
     print "threading: %d, store_value: %d" % (number, Test.store_value(key, value))
     time.sleep(10)
     print "threading: %d, release_value: %s" % (number, Test.release_value(key))
 if __name__ == "__main__":
     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)