Sharing and releasing python variables in multiple threads

The sharing and release of python class variables under multiple threads has recently been put into the trap by multiple threads. I am not aware that class variables are shared under multiple threads. Another problem is that I am not aware of the memory release problem, the more tired

1. python variables are shared in the case of multiple threads.

2. release of python variables in multi-thread mode is incomplete.

3. the memory that is not released when python variables are multithreading can be reused.

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)

Public data, unless read-only, should not be a class member variable. one is shared, and the other is not easy to release.