python - 如何彻底拆除数据库连接和 session ？

Question

当根据请求拆卸 sqlalchemy 连接时，以下是当前代码:

def init_request():
    engine = craete_engine(url)
    session = sessionmaker(bind=engine, autoflush=False)

def teardown():
    session.close()
    engine.dispose()

即使在session.close()之后也应该调用engine.dispose()吗？我不知道 session.close() 真的意味着拆除数据库连接。但是关于engine.dispose()，这个处理只是连接池而不是连接(写在文档上) http://docs.sqlalchemy.org/en/latest/core/connections.html

Answer 1

关闭 session 会删除所有连接资源并将它们返回到池中，请参阅 here .

The close() method issues a expunge_all(), and releases any transactional/connection resources. When connections are returned to the connection pool, transactional state is rolled back as well.

如果您没有执行任何额外操作，create_engine 将建立一个连接池，请参阅 here .

The Engine returned by the create_engine() function in most cases has a QueuePool integrated, pre-configured with reasonable pooling defaults.

如果您想在 session 关闭后释放连接(顺便说一句，我想知道为什么？)，我建议您改为禁用池(相同链接，下面几段)；这样您就可以避免每次都创建引擎。

Disabling pooling using NullPool:

from sqlalchemy.pool import NullPool
engine = create_engine(
          'postgresql+psycopg2://scott:tiger@localhost/test',
          poolclass=NullPool)