Sharing and releasing issues of python class variables under multi-threading-Python Tutorial-php.cn

I was tricked by multi-threading recently. I didn’t realize that class variables are shared under multi-threading. Another thing is that I didn’t realize the memory release problem, which made me more tired.

1. Python class variables in multi-threading situation The ones below are shared

2. The release of python class variables in multi-threaded situations is incomplete

3. The part of the memory that python class variables have not released in multi-threaded situations 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)

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Public Unless the data is read-only, do not use it as class member variables. First, it will be shared, and second, it will be difficult to release.