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在python下用sqlite3, 多线程 在UPDATE 或者INSERT的时候, 会报错
sqlite3.OperationalError: cannot commit - no transaction is active
1. 原因
多线程写冲突
- 非原子写操作：如果多个线程同时执行非原子写操作，可能会导致数据覆盖或不一致。
2. 解决方案
使用锁
使用锁来确保同一时间只有一个线程可以执行写操作。
import sqlite3
import threadinglock = threading.Lock()def worker(conn, thread_id):with lock:cursor = conn.cursor()cursor.execute("INSERT INTO test (id, value) VALUES (?, ?)", (thread_id, f"value_{thread_id}"))conn.commit()cursor.close()def main():conn = sqlite3.connect('example.db', check_same_thread=False)cursor = conn.cursor()cursor.execute("CREATE TABLE IF NOT EXISTS test (id INTEGER PRIMARY KEY, value TEXT)")conn.commit()cursor.close()threads = []for i in range(5):thread = threading.Thread(target=worker, args=(conn, i))threads.append(thread)thread.start()for thread in threads:thread.join()conn.close()if __name__ == "__main__":main()
使用事务
显式事务管理：在每个线程中显式地开始和提交事务，确保事务的原子性和一致性。
import sqlite3
import threadingdef worker(conn, thread_id):cursor = conn.cursor()cursor.execute("BEGIN")cursor.execute("INSERT INTO test (id, value) VALUES (?, ?)", (thread_id, f"value_{thread_id}"))conn.commit()cursor.close()def main():conn = sqlite3.connect('example.db', check_same_thread=False)cursor = conn.cursor()cursor.execute("CREATE TABLE IF NOT EXISTS test (id INTEGER PRIMARY KEY, value TEXT)")conn.commit()cursor.close()threads = []for i in range(5):thread = threading.Thread(target=worker, args=(conn, i))threads.append(thread)thread.start()for thread in threads:thread.join()conn.close()if __name__ == "__main__":main()