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Description:

djangodbgeventpool 4.0.7

django-db-geventpool

Another DB pool using gevent for PostgreSQL DB.
psycopg3
Django, since 4.2, supports psycopg3. One of the advantages is that gevent is supported without needing extra patches, just install the package
$ pip install psycopg[binary]

psycopg2
If gevent is not installed, the pool will use eventlet as fallback.

psycopg2>=2.5.1 for CPython 2 and 3 (or
psycopg2-binary---see
notes in the psycopg2 2.7.4
release)

psycopg2cffi>=2.7 for PyPy
Patch psycopg2
Before using the pool, psycopg2 must be patched with psycogreen, if you
are using gunicorn webserver, a good place
is the
post_fork()
function at the config file:
from psycogreen.gevent import patch_psycopg # use this if you use gevent workers
from psycogreen.eventlet import patch_psycopg # use this if you use eventlet workers

def post_fork(server, worker):
patch_psycopg()
worker.log.info("Made Psycopg2 Green")

Settings

Set ENGINE in your database settings to:
- For psycopg3: 'django_db_geventpool.backends.postgresql_psycopg3'
- For psycopg2: 'django_db_geventpool.backends.postgresql_psycopg2'
- For postgis: 'django_db_geventpool.backends.postgis'

Add MAX_CONNS to OPTIONS to set the maximun number of
connections allowed to database (default=4)

Add REUSE_CONNS to OPTIONS to indicate how many of the
MAX_CONNS should be reused by new requests. Will fallback to the
same value as MAX_CONNS if not defined

Add 'CONN_MAX_AGE': 0 to settings to disable default django
persistent connection feature. And read below note if you are
manually spawning greenlets

DATABASES = {
'default': {
'ENGINE': 'django_db_geventpool.backends.postgresql_psycopg',
'NAME': 'db',
'USER': 'postgres',
'PASSWORD': 'postgres',
'HOST': '',
'PORT': '',
'ATOMIC_REQUESTS': False,
'CONN_MAX_AGE': 0,
'OPTIONS': {
'MAX_CONNS': 20,
'REUSE_CONNS': 10
}
}
}

Using ORM when not serving requests
If you are using django with celery (or other), or have code that
manually spawn greenlets it will not be sufficient to set CONN_MAX_AGE
to 0. Django only checks for long-live connections when finishing a
request - So if you manually spawn a greenlet (or task spawning one) its
connections will not get cleaned up and will live until timeout. In
production this can cause quite some open connections and while
developing it can hamper your tests cases.
To solve it make sure that each greenlet function (or task) either sends
the django.core.signals.request_finished signal or calls
django.db.close_old_connections() right before it ends
The decorator method with your function is preferred, but the other
alternatives are also valid
from django_db_geventpool.utils import close_connection

@close_connection
def foo_func()
...

or
from django.core.signals import request_finished

def foo_func():
...
request_finished.send(sender="greenlet")

or
from django.db import close_old_connections

def foo_func():
...
close_old_connections()

Other pools

django-db-pool
django-postgresql