[FIX] base: Handle portal user deletion separately

Purpose
=======

Improve the portal user deletion by preventing timeouts and
avoiding several rollbacks causes.

Specifications
==============

- Move the portal users deletions from autovacuum to its own cron.
  On big databases such as odoo.com, deleting a res.users takes
  more than 1 minute. Move the whole process into its own scheduled
  tasks.
- Commit the deletion at each user. As said previously the deletion
  can be expensive, so commit what has been done to avoid having to
  delete the same user again in case of rollbacks or timeout.
- Delete the user and the partner separately. If the partner is used
  in a sales order for instance, the unlink is possible for the user
  and not the parner. It allows to unlink the user and keep the
  partner in case it cannot be deleted.
- Re-call the cron into another transaction in case there are too many
  users to delete, instead of waiting next call, that is supposed
  to occur the day after.

Taskid: 3222941
Part-of: odoo/odoo#114656

odoo/addons/base/data/ir_cron_data.xml

@@ -9,4 +9,14 @@
         <field name='interval_type'>days</field>
         <field name="numbercall">-1</field>
     </record>
+
+    <record id="ir_cron_res_users_deletion" model="ir.cron">
+        <field name="name">Base: Portal Users Deletion</field>
+        <field name="model_id" ref="base.model_res_users_deletion"/>
+        <field name="state">code</field>
+        <field name="code">model._gc_portal_users()</field>
+        <field name='interval_number'>1</field>
+        <field name='interval_type'>days</field>
+        <field name="numbercall">-1</field>
+    </record>
 </odoo>

odoo/addons/base/models/res_users_deletion.py

@@ -2,6 +2,7 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 import logging
+import threading
 
 
 from odoo import api, fields, models
@@ -35,8 +36,8 @@ class ResUsersDeletion(models.Model):
             if user_deletion.user_id:
                 user_deletion.user_id_int = user_deletion.user_id.id
 
-    @api.autovacuum
-    def _gc_portal_users(self):
+    @api.model
+    def _gc_portal_users(self, batch_size=10):
         """Remove the portal users that asked to deactivate their account.
 
         (see <res.users>::_deactivate_portal_user)
@@ -45,22 +46,55 @@ class ResUsersDeletion(models.Model):
         create_uid, write_uid on each models, which are not always indexed). Because of
         that, this operation is done in a CRON.
         """
-        delete_requests = self.search([('state', '=', 'todo')])
+        delete_requests = self.search([("state", "=", "todo")])
 
         # filter the requests related to a deleted user
         done_requests = delete_requests.filtered(lambda request: not request.user_id)
-        done_requests.state = 'done'
+        done_requests.state = "done"
 
-        for delete_request in (delete_requests - done_requests):
+        todo_requests = delete_requests - done_requests
+        batch_requests = todo_requests[:batch_size]
+
+        auto_commit = not getattr(threading.current_thread(), "testing", False)
+
+        for delete_request in batch_requests:
             user = delete_request.user_id
             user_name = user.name
+            requester_name = delete_request.create_uid.name
+            # Step 1: Delete User
             try:
-                with self.env.cr.savepoint():
-                    partner = user.partner_id
-                    user.unlink()
-                    partner.unlink()
-                    _logger.info('User #%i %r, deleted. Original request from %r.',
-                                 user.id, user_name, delete_request.create_uid.name)
-                    delete_request.state = 'done'
-            except Exception:
-                delete_request.state = 'fail'
+                self.env.cr.execute("SAVEPOINT delete_user")
+                partner = user.partner_id
+                user.unlink()
+                _logger.info("User #%i %r, deleted. Original request from %r.",
+                             user.id, user_name, delete_request.create_uid.name)
+                self.env.cr.execute("RELEASE SAVEPOINT delete_user")
+                delete_request.state = 'done'
+            except Exception as e:
+                _logger.error("User #%i %r could not be deleted. Original request from %r. Related error: %s",
+                             user.id, user_name, requester_name, e)
+                self.env.cr.execute("ROLLBACK TO SAVEPOINT delete_user")
+                delete_request.state = "fail"
+            # make sure we never rollback the work we've done, this can take a long time
+            if auto_commit:
+                self.env.cr.commit()
+            if delete_request.state == "fail":
+                continue
+
+            # Step 2: Delete Linked Partner
+            #         Could be impossible if the partner is linked to a SO for example
+            try:
+                self.env.cr.execute("SAVEPOINT delete_partner")
+                partner.unlink()
+                _logger.info("Partner #%i %r, deleted. Original request from %r.",
+                             partner.id, user_name, delete_request.create_uid.name)
+                self.env.cr.execute("RELEASE SAVEPOINT delete_partner")
+            except Exception as e:
+                _logger.warning("Partner #%i %r could not be deleted. Original request from %r. Related error: %s",
+                             partner.id, user_name, requester_name, e)
+                self.env.cr.execute("ROLLBACK TO SAVEPOINT delete_partner")
+            # make sure we never rollback the work we've done, this can take a long time
+            if auto_commit:
+                self.env.cr.commit()
+        if len(todo_requests) > batch_size:
+            self.env.ref("base.ir_cron_res_users_deletion")._trigger()

odoo/addons/base/tests/test_res_users.py

@@ -133,7 +133,7 @@ class TestUsers(TransactionCase):
         with self.assertRaises(UserError, msg='Internal users should not be able to deactivate their account'):
             user_internal._deactivate_portal_user()
 
-    @mute_logger('odoo.sql_db')
+    @mute_logger('odoo.sql_db', 'odoo.addons.base.models.res_users_deletion')
     def test_deactivate_portal_users_archive_and_remove(self):
         """Test that if the account can not be removed, it's archived instead
         and sensitive information are removed.