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Add warnings and recommendations to docs about timeout-related connection leaks #729

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Add warnings and recommendations to docs about timeout-related connection leaks #729

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abb22c0
Connection pooling recommendations
Aug 4, 2022
67af877
Update docs
Aug 4, 2022
dd7a547
Fix spacing
Aug 4, 2022
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8 changes: 8 additions & 0 deletions docs/api/baseplate/clients/sqlalchemy.rst
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Expand Up @@ -52,6 +52,14 @@ request::
Configuration
-------------

.. warning::

:py:class:`sqlalchemy.pool.QueuePool` does not handle `ServerTimeout`
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Is there a code example of how to do this the right way vs wrong way? That'd be great to include here

(generally I prefer it when saying "Don't do it this way" to guide people through the right way of doing it (though the starting pointers of "do this instead" helps a lot))

exceptions gracefully, potentially leaking connections. It is recommended
to avoid local pooling entirely (via :py:class:`sqlalchemy.pool.NullPool`)
while this issue persists and instead rely on middleware pooling (such as
`pgbouncer`).

.. autoclass:: SQLAlchemySession

.. autofunction:: engine_from_config
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8 changes: 8 additions & 0 deletions docs/api/baseplate/observers/timeout.rst
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Expand Up @@ -14,6 +14,14 @@ upstream services are yet taken into account.
taking a long time because it is doing compute-heavy actions and not
yielding to the event loop it might go on longer than the allotted timeout.

.. warning::

The timeout mechanism may throw a `ServerTimeout` exception whenever a gevent
context switch occurs. If this exception is not handled gracefully your
application could get stuck in a bad state. For example, if a `ServerTimeout`
exception is thrown while releasing a connection then the connection might
never be fully released.

.. versionadded:: 1.2

.. versionchanged:: 1.3.3
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