openstack/oslo.messaging
Code Issues Proposed changes

Cancel consumer if queue down

Browse Source 
Previously, we have switched to use default exchanges
to avoid excessive amounts of exchange not found messages.
But it does not actually solve the problem because
reply_* queue is already gone and agent will not receive callbacks.

after some debugging, I found under some circumstances
seems rabbitmq consumer does not receive basic cancel
signal when queue is already gone. This might due to
rabbitmq try to restart consumer when queue is down
(for example when split brain). In such cases,
it might be better to fail early.

by reading the code, seems like x-cancel-on-ha-failover
is not dedicated to mirror queues only, https://github.com/rabbitmq/rabbitmq-server/blob/master/src/rabbit_channel.erl#L1894,
https://github.com/rabbitmq/rabbitmq-server/blob/master/src/rabbit_channel.erl#L1926.

By failing early, in my own test setup,
I could solve a certain case of exchange not found problem.

Change-Id: I2ae53340783e4044dab58035bc0992dc08145b53
Related-bug: #1789177
This commit is contained in:
shenjiatong 2020-07-03 15:51:21 +08:00 committed by ushen
parent 7e406c312a
commit 196fa877a9
3 changed files with 65 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
oslo_messaging/_drivers/impl_rabbit.py
View File

@ -172,6 +172,11 @@ rabbit_opts = [
'for direct send. The direct send is used as reply, '
'so the MessageUndeliverable exception is raised '
'in case the client queue does not exist.'),
cfg.BoolOpt('enable_cancel_on_failover',
default=False,
help="Enable x-cancel-on-ha-failover flag so that "
"rabbitmq server will cancel and notify consumers"
"when queue is down")
]
LOG = logging.getLogger(__name__)
@ -233,7 +238,8 @@ class Consumer(object):
def __init__(self, exchange_name, queue_name, routing_key, type, durable,
exchange_auto_delete, queue_auto_delete, callback,
nowait=False, rabbit_ha_queues=None, rabbit_queue_ttl=0):
nowait=False, rabbit_ha_queues=None, rabbit_queue_ttl=0,
enable_cancel_on_failover=False):
"""Init the Consumer class with the exchange_name, routing_key,
type, durable auto_delete
"""
@ -255,10 +261,16 @@ class Consumer(object):
type=type,
durable=self.durable,
auto_delete=self.exchange_auto_delete)
self.enable_cancel_on_failover = enable_cancel_on_failover
def declare(self, conn):
"""Re-declare the queue after a rabbit (re)connect."""
consumer_arguments = None
if self.enable_cancel_on_failover:
consumer_arguments = {
"x-cancel-on-ha-failover": True}
self.queue = kombu.entity.Queue(
name=self.queue_name,
channel=conn.channel,
@ -266,7 +278,9 @@ class Consumer(object):
durable=self.durable,
auto_delete=self.queue_auto_delete,
routing_key=self.routing_key,
queue_arguments=self.queue_arguments)
queue_arguments=self.queue_arguments,
consumer_arguments=consumer_arguments
)
try:
LOG.debug('[%s] Queue.declare: %s',
@ -467,6 +481,7 @@ class Connection(object):
self.kombu_failover_strategy = driver_conf.kombu_failover_strategy
self.kombu_compression = driver_conf.kombu_compression
self.heartbeat_in_pthread = driver_conf.heartbeat_in_pthread
self.enable_cancel_on_failover = driver_conf.enable_cancel_on_failover
if self.heartbeat_in_pthread:
# NOTE(hberaud): Experimental: threading module is in use to run
@ -1116,31 +1131,35 @@ class Connection(object):
responses for call/multicall
"""
consumer = Consumer(exchange_name='', # using default exchange
queue_name=topic,
routing_key='',
type='direct',
durable=False,
exchange_auto_delete=False,
queue_auto_delete=False,
callback=callback,
rabbit_ha_queues=self.rabbit_ha_queues,
rabbit_queue_ttl=self.rabbit_transient_queues_ttl)
consumer = Consumer(
exchange_name='', # using default exchange
queue_name=topic,
routing_key='',
type='direct',
durable=False,
exchange_auto_delete=False,
queue_auto_delete=False,
callback=callback,
rabbit_ha_queues=self.rabbit_ha_queues,
rabbit_queue_ttl=self.rabbit_transient_queues_ttl,
enable_cancel_on_failover=self.enable_cancel_on_failover)
self.declare_consumer(consumer)
def declare_topic_consumer(self, exchange_name, topic, callback=None,
queue_name=None):
"""Create a 'topic' consumer."""
consumer = Consumer(exchange_name=exchange_name,
queue_name=queue_name or topic,
routing_key=topic,
type='topic',
durable=self.amqp_durable_queues,
exchange_auto_delete=self.amqp_auto_delete,
queue_auto_delete=self.amqp_auto_delete,
callback=callback,
rabbit_ha_queues=self.rabbit_ha_queues)
consumer = Consumer(
exchange_name=exchange_name,
queue_name=queue_name or topic,
routing_key=topic,
type='topic',
durable=self.amqp_durable_queues,
exchange_auto_delete=self.amqp_auto_delete,
queue_auto_delete=self.amqp_auto_delete,
callback=callback,
rabbit_ha_queues=self.rabbit_ha_queues,
enable_cancel_on_failover=self.enable_cancel_on_failover)
self.declare_consumer(consumer)
@ -1151,16 +1170,18 @@ class Connection(object):
exchange_name = '%s_fanout' % topic
queue_name = '%s_fanout_%s' % (topic, unique)
consumer = Consumer(exchange_name=exchange_name,
queue_name=queue_name,
routing_key=topic,
type='fanout',
durable=False,
exchange_auto_delete=True,
queue_auto_delete=False,
callback=callback,
rabbit_ha_queues=self.rabbit_ha_queues,
rabbit_queue_ttl=self.rabbit_transient_queues_ttl)
consumer = Consumer(
exchange_name=exchange_name,
queue_name=queue_name,
routing_key=topic,
type='fanout',
durable=False,
exchange_auto_delete=True,
queue_auto_delete=False,
callback=callback,
rabbit_ha_queues=self.rabbit_ha_queues,
rabbit_queue_ttl=self.rabbit_transient_queues_ttl,
enable_cancel_on_failover=self.enable_cancel_on_failover)
self.declare_consumer(consumer)

7
oslo_messaging/tests/functional/test_rabbitmq.py
View File

@ -39,6 +39,12 @@ class RabbitMQFailoverTests(test_utils.BaseTestCase):
]
def test_failover_scenario(self):
self._test_failover_scenario()
def test_failover_scenario_enable_cancel_on_failover(self):
self._test_failover_scenario(enable_cancel_on_failover=True)
def _test_failover_scenario(self, enable_cancel_on_failover=False):
# NOTE(sileht): run this test only if functional suite run of a driver
# that use rabbitmq as backend
self.driver = os.environ.get('TRANSPORT_DRIVER')
@ -53,6 +59,7 @@ class RabbitMQFailoverTests(test_utils.BaseTestCase):
kombu_reconnect_delay=0,
rabbit_retry_interval=0,
rabbit_retry_backoff=0,
enable_cancel_on_failover=enable_cancel_on_failover,
group='oslo_messaging_rabbit')
self.pifpaf = self.useFixture(rabbitmq.RabbitMQDriver(cluster=True,

6
releasenotes/notes/add-enable_cancel_on_failover-22ac472b93dd3a23.yaml Normal file
View File

@ -0,0 +1,6 @@
---
fixes:
- |
Add a new option `enable_cancel_on_failover` for rabbitmq driver
which when enabled, will cancel consumers when queue appears
to be down.