Oh, I see. I was unaware that lambda evaluated the result only once,
not each use. Thanks so much for your help.
On Dec 19, 4:36 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
> def setup(**kwargs):
> connection = MySQLdb.connections.Connection(**kwargs)
> engine = create_engine('mysql://', creator=lambda: connection,
> pool_recycle=2)
>
> the "creator" argument is a callable that returns a new connection
> when the pool needs one. Above, you are pre-connecting a single MySQL
> connection and returning it from the lambda. Besides producing non-
> mutexed multithreaded access to the single Connection itself (which
> may or may not be OK for MySQLdb), it also prevents a new connection
> from being created once it has been recycled. The previous
> connection, now closed, is all that's available.
>
> The correct form is:
>
> def setup(**kwargs):
> def connect():
> return MySQLdb.connections.Connection(**kwargs)
> engine = create_engine('mysql://', creator=lambda: connect,
> pool_recycle=2)
>
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