[IMP] Make default subchannel capacity configurable.

Either ODOO_QUEUE_JOB_DEFAULT_SUBCHANNEL_CAPACITY may be set as
an environment variable, or default_subchannel_capacity may be set
in the [queue_job] config file stanza.

queue_job/jobrunner/channels.py

@@ -2,12 +2,14 @@
 # Copyright 2015-2016 Camptocamp SA
 # License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html)
 import logging
+import os
 from functools import total_ordering
 from heapq import heappop, heappush
 from weakref import WeakValueDictionary
 
 from ..exception import ChannelNotFound
 from ..job import CANCELLED, DONE, ENQUEUED, FAILED, PENDING, STARTED, WAIT_DEPENDENCIES
+from . import queue_job_config
 
 NOT_DONE = (WAIT_DEPENDENCIES, PENDING, ENQUEUED, STARTED, FAILED)
 
@@ -411,7 +413,7 @@ def __init__(self, name, parent, capacity=None, sequential=False, throttle=0):
         self._running = SafeSet()
         self._failed = SafeSet()
         self._pause_until = 0  # utc seconds since the epoch
-        self.capacity = capacity
+        self.capacity = capacity or _default_subchannel_capacity()
         self.throttle = throttle  # seconds
         self.sequential = sequential
 
@@ -933,7 +935,7 @@ def get_channel_from_config(self, config):
         If the channel does not exist it is created.
         The configuration is applied on the channel before returning it.
         If some of the parent channels are missing when creating a subchannel,
-        the parent channels are auto created with an infinite capacity
+        the parent channels are auto created with the default subchannel capacity
         (except for the root channel, which defaults to a capacity of 1
         when not configured explicity).
         """
@@ -1077,3 +1079,11 @@ def get_jobs_to_run(self, now):
 
     def get_wakeup_time(self):
         return self._root_channel.get_wakeup_time()
+
+
+def _default_subchannel_capacity():
+    capacity = os.environ.get(
+        "ODOO_QUEUE_JOB_DEFAULT_SUBCHANNEL_CAPACITY"
+    ) or queue_job_config.get("default_subchannel_capacity")
+    if capacity:
+        return int(capacity)

queue_job/readme/CONFIGURE.rst

@@ -5,6 +5,9 @@
     - ``ODOO_QUEUE_JOB_CHANNELS=root:4`` or any other channels configuration.
       The default is ``root:1``
 
+    - ``ODOO_QUEUE_JOB_DEFAULT_SUBCHANNEL_CAPACITY=1``
+      The default is infinite capacity.
+
     - if ``xmlrpc_port`` is not set: ``ODOO_QUEUE_JOB_PORT=8069``
 
   * Start Odoo with ``--load=web,queue_job``
@@ -23,6 +26,7 @@
   (...)
   [queue_job]
   channels = root:2
+  # default_subchannel_capacity = 1
 
 * Confirm the runner is starting correctly by checking the odoo log file:
 

queue_job/tests/test_runner_channels.py

@@ -1,10 +1,28 @@
 # Copyright 2015-2016 Camptocamp SA
 # License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html)
 
+import os
+from unittest.mock import patch
+
+from odoo.tests import BaseCase
+
 # pylint: disable=odoo-addons-relative-import
 # we are testing, we want to test as we were an external consumer of the API
 from odoo.addons.queue_job.jobrunner import channels
 
 from .common import load_doctests
 
 load_tests = load_doctests(channels)
+
+
+class TestDefaultSubchannelCapacity(BaseCase):
+    @patch.dict(os.environ, {"ODOO_QUEUE_JOB_DEFAULT_SUBCHANNEL_CAPACITY": "1"})
+    def test_default_subchannel_capacity_env(self):
+        self.assertEqual(channels._default_subchannel_capacity(), 1)
+
+    @patch.dict(channels.queue_job_config, {"default_subchannel_capacity": "1"})
+    def test_default_subchannel_capacity_conf(self):
+        self.assertEqual(channels._default_subchannel_capacity(), 1)
+
+    def test_default_subchannel_capacity_omit(self):
+        self.assertIs(channels._default_subchannel_capacity(), None, "oops")