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.
Also, does this setting prevent pool invalidation on all sort of exceptions 
related to connections?

@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
>>
>>
>> -- 
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>> The Python SQL Toolkit and Object Relational Mapper
>>  
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