关于 MySQL 连接失效的问题

[Ed-XCF]

sqlalchemy 有三个 配置 可能可以帮助解决问题。具体的设置值还需要更多资料和实践支持：

增加连接池内连接数
:param pool_size=5: the number of connections to keep open
inside the connection pool. This used with
:class:~sqlalchemy.pool.QueuePool as
well as :class:~sqlalchemy.pool.SingletonThreadPool. With
:class:~sqlalchemy.pool.QueuePool, a pool_size setting
of 0 indicates no limit; to disable pooling, set poolclass to
:class:~sqlalchemy.pool.NullPool instead.

定期完全重置连接池
:param pool_recycle=-1: this setting causes the pool to recycle
connections after the given number of seconds has passed. It
defaults to -1, or no timeout. For example, setting to 3600
means connections will be recycled after one hour. Note that
MySQL in particular will disconnect automatically if no
activity is detected on a connection for eight hours (although
this is configurable with the MySQLDB connection itself and the
server configuration as well).

连接前进行 " 预 ping "（在直接使用 pymysql 编程的场景下，它是一种可以工作的策略，尚不清楚对运行中的事务的影响）
:param pool_pre_ping: boolean, if True will enable the connection pool
"pre-ping" feature that tests connections for liveness upon
each checkout.