id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
34914	Postgres connection is not restarted after it's dropped by the server, even if we use CONN_HEALTH_CHECKS=True	Vitor Menegat	nobody	"I'm using a Django management command to start a container that executes DB queries (without any transaction scope): `python manage.py <mycommand>`

These are the relevant database configs I'm using:
{{{
DATABASES = {
    ""default"": env.db(""DATABASE_URL""),
}

DATABASES[""default""][""ATOMIC_REQUESTS""] = True
DATABASES[""default""][""CONN_HEALTH_CHECKS""] = True
DATABASES[""default""][""CONN_MAX_AGE""] = None                  ### I've also tried setting this to 0. Same issue
}}}

When Django loses the DB connection for whatever reason, I see the error `server closed the connection unexpectedly`, but then the error `psycopg2.InterfaceError: connection already closed` happens over and over again, every time it tries to execute a SQL query. This is very annoying because the container needs to be re-created in other for the app to function properly.

Investigating this I found here that the connection health check is SKIPPED if (https://github.com/django/django/blob/main/django/db/backends/base/base.py#L576-L580):
* self.connection is None; OR
* self.health_checks_enabled = False; OR
* self.health_check_done = True

I created a test command to understand what was happening with the connection, added some logs to see the connection attributes, and found that the connection health check is always skipped because `self.health_check_done` is never set to False.

**My question is:** shouldn't the connection be health checked when `self.errors_occurred` flips to True?

Here's the code I used to test:

{{{
import logging
import time 

from django.core.management import BaseCommand
from django.db import connection


logger = logging.getLogger(__name__)


class Command(BaseCommand):
    help = """"

    def handle(self, *args, **kwargs):
        while True:
            time.sleep(1)
            try:
                logger.info(f""health_check_enabled: {connection.health_check_enabled}"")
                logger.info(f""health_check_done: {connection.health_check_done}"")
                logger.info(f""errors_occurred: {connection.errors_occurred}"")
                with connection.cursor() as cursor:
                    cursor.execute(""SELECT 1"")
                logger.info(""query executed"")
            except Exception as e:
                logger.exception(e)
}}}

Here's the relevant part of the logs:

{{{
health_check_enabled: False   ## the connect() method was not yet called
health_check_done: False      ## the connect() method was not yet called
errors_occurred: False

query executed

health_check_enabled: True
health_check_done: True
errors_occurred: False

server closed the connection unexpectedly
	This probably means the server terminated abnormally
	before or while processing the request.
Traceback (most recent call last):
  File ""/usr/local/lib/python3.11/site-packages/django/db/backends/utils.py"", line 87, in _execute
    return self.cursor.execute(sql)
           ^^^^^^^^^^^^^^^^^^^^^^^^
psycopg2.OperationalError: server closed the connection unexpectedly
    This probably means the server terminated abnormally
    before or while processing the request.
[... Traceback omitted ...]

health_check_enabled: True
health_check_done: True
errors_occurred: True         ## This is set to True now, as expected

Traceback (most recent call last):
  File ""/usr/local/lib/python3.11/site-packages/django/db/backends/base/base.py"", line 308, in _cursor
    return self._prepare_cursor(self.create_cursor(name))
                                ^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/utils/asyncio.py"", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/db/backends/postgresql/base.py"", line 330, in create_cursor
    cursor = self.connection.cursor()
             ^^^^^^^^^^^^^^^^^^^^^^^^
psycopg2.InterfaceError: connection already closed
[...Traceback omitted ...]

health_check_enabled: True
health_check_done: True
errors_occurred: True

Traceback (most recent call last):
  File ""/usr/local/lib/python3.11/site-packages/django/db/backends/base/base.py"", line 308, in _cursor
    return self._prepare_cursor(self.create_cursor(name))
                                ^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/utils/asyncio.py"", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/db/backends/postgresql/base.py"", line 330, in create_cursor
    cursor = self.connection.cursor()
             ^^^^^^^^^^^^^^^^^^^^^^^^
psycopg2.InterfaceError: connection already closed
[... Traceback omitted ...]

health_check_enabled: True
health_check_done: True
errors_occurred: True

Traceback (most recent call last):
  File ""/usr/local/lib/python3.11/site-packages/django/db/backends/base/base.py"", line 308, in _cursor
    return self._prepare_cursor(self.create_cursor(name))
                                ^^^^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/utils/asyncio.py"", line 26, in inner
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File ""/usr/local/lib/python3.11/site-packages/django/db/backends/postgresql/base.py"", line 330, in create_cursor
    cursor = self.connection.cursor()
             ^^^^^^^^^^^^^^^^^^^^^^^^
psycopg2.InterfaceError: connection already closed
[... Traceback omitted ...]
}}}
"	Bug	closed	Database layer (models, ORM)	4.2	Normal	duplicate		Vitor Menegat Marcelo Frantz	Unreviewed	0	0	0	0	0	0