Metadata-Version: 2.1
Name: odoo-addon-bus_alt_connection
Version: 18.0.1.0.0.2
Requires-Python: >=3.10
Requires-Dist: odoo==18.0.*
Summary: Needed when using PgBouncer as a connection pooler
Home-page: https://github.com/OCA/server-tools
License: AGPL-3
Author: Trobz,Odoo Community Association (OCA)
Author-email: support@odoo-community.org
Classifier: Programming Language :: Python
Classifier: Framework :: Odoo
Classifier: Framework :: Odoo :: 18.0
Classifier: License :: OSI Approved :: GNU Affero General Public License v3
Description-Content-Type: text/x-rst

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==================
Bus Alt Connection
==================

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This module makes it possible to use
`PgBouncer <https://pgbouncer.github.io/>`__ as a connection pooler for
odoo.

Why isn't odoo's connection pooling good enough?
------------------------------------------------

Odoo's builtin connection pooling works at process level: each Odoo
process has its own
`ConnectionPool <https://github.com/odoo/odoo/blob/12.0/odoo/sql_db.py#L525>`__,
limited to ``db_maxconn``.

It does the job of re-using open connections available in the pool. But
it never closes these connections, `unless reaching
db_maxconn <https://github.com/odoo/odoo/blob/12.0/odoo/sql_db.py#L593>`__.

In practice, we observe that each odoo worker will end up with up to 3
open connection in its pool. With 10 http workers, that's up to 30
connection continuously open just for one single instance.

Here comes PgBouncer
--------------------

PgBouncer will help to limit this number of open connections, by sharing
a pool of connections at the instance level, between all workers. Odoo
workers will still have up to 3 open connections, but these will be
connections to PgBouncer, that on its side will close unnecessary
connections to pg.

This has proven to help performances on Odoo deployments with multiple
instances.

It allows you to define how resources should be shared, according to
your priorities, e.g. :

- key odoo instance on host A can open up to 30 connections
- while odoo instance on host B, dedicated to reports, can open up to 10
  connections only

And most importantly, it helps you to ensure that ``max_connections``
will never be reached on pg server side.

Why is this module needed?
--------------------------

When configuring PgBouncer, you can choose between 2 transaction pooling
modes:

- pool_mode = session
- pool_mode = transaction

If we choose pool_mode = session, then one server connection will be
tied to a given odoo process until its death, which is exactly what
we're trying to change. Thus, to release the server connection once the
transaction is complete, we use pool_mode = transaction.

This works fine, except for Odoo's longpolling features that relies on
the
`LISTEN/NOTIFY <https://www.postgresql.org/docs/9.6/static/sql-notify.html>`__
mechanism from pg, which is `not
compatible <https://wiki.postgresql.org/wiki/PgBouncer>`__ with that
mode.

To be more precise, NOTIFY statements are properly transfered by
PgBouncer in that mode; only the LISTEN statement isn't (because it
needs to keep the server connection open).

So for the unique "listening" connection per instance that requires this
statement
(`here <https://github.com/odoo/odoo/blob/12.0/addons/bus/models/bus.py#L166>`__),
we need odoo to connect directly to the pg server, bypassing PgBouncer.

That's what this module implements, by overriding the relevant method of
the
`Dispatcher <https://github.com/odoo/odoo/blob/12.0/addons/bus/models/bus.py#L105>`__.

**Table of contents**

.. contents::
   :local:

Installation
============

You don't need to install this module in the database(s) to enable it.

But you need to load it server-wide:

- By starting Odoo with ``--load=web,bus_alt_connection``
- Or by updating its configuration file:

.. code:: ini

   [options]
   (...)
   server_wide_modules = web,bus_alt_connection

Configuration
=============

You need to define how to connect directly to the database:

- Either by defining environment variables:

     - ``IMDISPATCHER_DB_HOST=db-01``
     - ``IMDISPATCHER_DB_PORT=5432``

- Or in Odoo's configuration file:

.. code:: ini

   [options]
   (...)
   imdispatcher_db_host = db-01
   imdispatcher_db_port = 5432

Bug Tracker
===========

Bugs are tracked on `GitHub Issues <https://github.com/OCA/server-tools/issues>`_.
In case of trouble, please check there if your issue has already been reported.
If you spotted it first, help us to smash it by providing a detailed and welcomed
`feedback <https://github.com/OCA/server-tools/issues/new?body=module:%20bus_alt_connection%0Aversion:%2018.0%0A%0A**Steps%20to%20reproduce**%0A-%20...%0A%0A**Current%20behavior**%0A%0A**Expected%20behavior**>`_.

Do not contact contributors directly about support or help with technical issues.

Credits
=======

Authors
-------

* Trobz

Contributors
------------

- Nils Hamerlinck <nils@trobz.com>

Maintainers
-----------

This module is maintained by the OCA.

.. image:: https://odoo-community.org/logo.png
   :alt: Odoo Community Association
   :target: https://odoo-community.org

OCA, or the Odoo Community Association, is a nonprofit organization whose
mission is to support the collaborative development of Odoo features and
promote its widespread use.

This module is part of the `OCA/server-tools <https://github.com/OCA/server-tools/tree/18.0/bus_alt_connection>`_ project on GitHub.

You are welcome to contribute. To learn how please visit https://odoo-community.org/page/Contribute.
