cx-oracle SessionPool is used underlying that will probe connections on checkout and recover. Hence, trying to disable SQLAlchemy invalidate pool. Thanks! On Monday, January 10, 2022 at 12:04:57 PM UTC-8 Mike Bayer wrote:
> > > On Mon, Jan 10, 2022, at 1:30 PM, Anupama Goparaju wrote: > > Thanks. Looks like this works but we need to set it for every exception > scenario. Just confirming if the exception_context is thread safe to set > the attribute. > > > yes this all happens local to the execute() function call, is not exposed > to threads > > > Also, does this setting prevent pool invalidation on all sort of > exceptions related to connections? > > > yes, the pathway by which getting an exception would lead to invalidating > the connection is blocked by this event handler. I'm not sure why you'd > want to set that in all cases as there are legitimate "disconnect" error > scenarios (such as database was stopped and restarted), unless you are > doing something with the DBAPI connection that allows it to recover by > itself, I guess. > > > @event.listens_for(Engine, *'handle_error'*) > def receive_handle_error(exception_context): > if exception_context.invalidate_pool_on_disconnect: > exception_context.invalidate_pool_on_disconnect = False > > On Thursday, January 6, 2022 at 10:03:55 AM UTC-8 Anupama Goparaju wrote: > > Thanks, i will give it a try. > > On Thursday, January 6, 2022 at 5:23:09 AM UTC-8 Mike Bayer wrote: > > > I can't guarantee that overriding private methods is safe, no. > > there's a public API to disable errors resulting in invalidation, I > suggest you use that. > > > > On Wed, Jan 5, 2022, at 7:35 PM, Anupama Goparaju wrote: > > I haven't read the response before and tried to skip the lib logic by > overriding the function below in my child call extending the NullPool to do > nothing. Is this safe to do? > > def _invalidate(self, connection, exception=None, _checkin=True): > pass > > On Wednesday, January 5, 2022 at 4:33:01 PM UTC-8 Anupama Goparaju wrote: > > Great, thanks for the info. > > On Friday, November 26, 2021 at 9:30:02 AM UTC-8 Mike Bayer wrote: > > > I've spent some time thinking about what might be being asked here. the > only thing I can think of is that when a particular database connection is > found to be in what we call a "disconnect" state, the connection is > invalidated, so that the connection will reconnect and make a new > connection. But also, this operation will typically assume the > "disconnect" condition is that the database was restarted, or some other > network condition has probably made all the connections that are pooled > also invalid. So the entire pool will be invalidated in this case as well. > > Why someone might want to turn that off is if they are getting lots of > invalidated connections for some other reason and they are not able to > solve that problem, so they'd like the pool to not be invalidated totally. > This means that if the database is restarted, and for example you have 20 > pooled connections, you will in a high-request environment get up to 20 > server errors unless pool_pre_ping is turned on so that the connections are > refreshed one at at time. > > To disable the pool invalidation upon receipt of a single connection shown > to be in a disconnect, implement the handle_error event: > https://docs.sqlalchemy.org/en/14/core/events.html#sqlalchemy.events.ConnectionEvents.handle_error > > and then set invalidate_pool_on_disconnect to False: > https://docs.sqlalchemy.org/en/14/core/connections.html?highlight=invalidate_pool_on_disconnect#sqlalchemy.engine.ExceptionContext.invalidate_pool_on_disconnect > > . > > > > On Fri, Nov 26, 2021, at 11:51 AM, Mike Bayer wrote: > > Im not sure if I understand the question? if you don't call > .invalidate(), then the connection is not invalidated. > > what does "turn off" mean ? > > > > On Fri, Nov 26, 2021, at 11:17 AM, Anupama Goparaju wrote: > > Hi, > > Is there a way to safely turn off connection invalidation functionality > (based on invalidation time set, all the connections created prior to the > timestamp are invalidated) in sqlalchemy? > > > https://github.com/Noethys/Connecthys/blob/master/connecthys/lib/sqlalchemy/pool.py#L574 > > Thanks, > Anupama > > > -- > SQLAlchemy - > The Python SQL Toolkit and Object Relational Mapper > > http://www.sqlalchemy.org/ > > To post example code, please provide an MCVE: Minimal, Complete, and > Verifiable Example. 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