openstack/oslo.messaging
Code Issues Proposed changes

Don't reply when we known that client is gone

Browse Source 
In case of a broker restart/failover a reply queue can be
unreachable for short period the IncomingMessage.send_reply
will block for 60 seconds in this case or until rabbit recovers.

But in case of the reply queue is unreachable because the
rpc client is really gone, we can have a ton of reply to send
waiting 60 seconds.
This leads to a starvation of connection of the pool
The rpc server take to much time to send reply, other rpc client will
raise TimeoutError because their don't receive their replies in time.

This changes introduces an object cache that stores already known gone
client to not wait 60 seconds and hold a connection of the pool
Keeping 200 last gone rpc client for 1 minute is enough
and doesn't hold to much memory.

This also don't raise anymore a frightening exception when we can't send reply
to the rpc client. But just logging a info about missing exchange and
a warning about unsend reply.

Closes-bug: #1460652

Change-Id: I928b30c9b5f9ee007532ff703e136640b0e8aaf4
This commit is contained in:
Mehdi Abaakouk 2015-06-17 18:45:24 +02:00 committed by Victor Sergeyev
parent 8dc5923a98
commit 286659a38b
5 changed files with 124 additions and 7 deletions

4
oslo_messaging/_drivers/amqp.py

@ -263,3 +263,7 @@ def _add_unique_id(msg):
"""Add unique_id for checking duplicate messages."""
unique_id = uuid.uuid4().hex
msg.update({UNIQUE_ID: unique_id})
class AMQPDestinationNotFound(Exception):
pass

76
oslo_messaging/_drivers/amqpdriver.py

@ -19,6 +19,7 @@ import logging
import threading
import uuid
import cachetools
from six import moves
import oslo_messaging
@ -27,13 +28,15 @@ from oslo_messaging._drivers import base
from oslo_messaging._drivers import common as rpc_common
from oslo_messaging._i18n import _
from oslo_messaging._i18n import _LI
from oslo_messaging._i18n import _LW
LOG = logging.getLogger(__name__)
class AMQPIncomingMessage(base.IncomingMessage):
def __init__(self, listener, ctxt, message, unique_id, msg_id, reply_q):
def __init__(self, listener, ctxt, message, unique_id, msg_id, reply_q,
obsolete_reply_queues):
super(AMQPIncomingMessage, self).__init__(listener, ctxt,
dict(message))
@ -42,9 +45,15 @@ class AMQPIncomingMessage(base.IncomingMessage):
self.reply_q = reply_q
self.acknowledge_callback = message.acknowledge
self.requeue_callback = message.requeue
self._obsolete_reply_queues = obsolete_reply_queues
def _send_reply(self, conn, reply=None, failure=None,
ending=False, log_failure=True):
if (self.reply_q and
not self._obsolete_reply_queues.reply_q_valid(self.reply_q,
self.msg_id)):
return
if failure:
failure = rpc_common.serialize_remote_exception(failure,
log_failure)
@ -60,8 +69,15 @@ class AMQPIncomingMessage(base.IncomingMessage):
# Otherwise use the msg_id for backward compatibility.
if self.reply_q:
msg['_msg_id'] = self.msg_id
conn.direct_send(self.reply_q, rpc_common.serialize_msg(msg))
try:
conn.direct_send(self.reply_q, rpc_common.serialize_msg(msg))
except rpc_amqp.AMQPDestinationNotFound:
self._obsolete_reply_queues.add(self.reply_q, self.msg_id)
else:
# TODO(sileht): look at which version of oslo-incubator rpc
# send need this, but I guess this is older than icehouse
# if this is icehouse, we can drop this at M
# if this is havana, we can drop this now.
conn.direct_send(self.msg_id, rpc_common.serialize_msg(msg))
def reply(self, reply=None, failure=None, log_failure=True):
@ -69,6 +85,13 @@ class AMQPIncomingMessage(base.IncomingMessage):
# NOTE(Alexei_987) not sending reply, if msg_id is empty
# because reply should not be expected by caller side
return
# NOTE(sileht): return without hold the a connection if possible
if (self.reply_q and
not self._obsolete_reply_queues.reply_q_valid(self.reply_q,
self.msg_id)):
return
with self.listener.driver._get_connection(
rpc_amqp.PURPOSE_SEND) as conn:
if self.listener.driver.send_single_reply:
@ -92,6 +115,51 @@ class AMQPIncomingMessage(base.IncomingMessage):
self.requeue_callback()
class ObsoleteReplyQueuesCache(object):
"""Cache of reply queue id that doesn't exists anymore.
NOTE(sileht): In case of a broker restart/failover
a reply queue can be unreachable for short period
the IncomingMessage.send_reply will block for 60 seconds
in this case or until rabbit recovers.
But in case of the reply queue is unreachable because the
rpc client is really gone, we can have a ton of reply to send
waiting 60 seconds.
This leads to a starvation of connection of the pool
The rpc server take to much time to send reply, other rpc client will
raise TimeoutError because their don't receive their replies in time.
This object cache stores already known gone client to not wait 60 seconds
and hold a connection of the pool.
Keeping 200 last gone rpc client for 1 minute is enough
and doesn't hold to much memory.
"""
SIZE = 200
TTL = 60
def __init__(self):
self._lock = threading.RLock()
self._cache = cachetools.TTLCache(self.SIZE, self.TTL)
def reply_q_valid(self, reply_q, msg_id):
if reply_q in self._cache:
self._no_reply_log(reply_q, msg_id)
return False
return True
def add(self, reply_q, msg_id):
with self._lock:
self._cache.update({reply_q: msg_id})
self._no_reply_log(reply_q, msg_id)
def _no_reply_log(self, reply_q, msg_id):
LOG.warn(_LW("%(reply_queue)s doesn't exists, drop reply to "
"%(msg_id)s"), {'reply_queue': reply_q,
'msg_id': msg_id})
class AMQPListener(base.Listener):
def __init__(self, driver, conn):
@ -100,6 +168,7 @@ class AMQPListener(base.Listener):
self.msg_id_cache = rpc_amqp._MsgIdCache()
self.incoming = []
self._stopped = threading.Event()
self._obsolete_reply_queues = ObsoleteReplyQueuesCache()
def __call__(self, message):
ctxt = rpc_amqp.unpack_context(self.conf, message)
@ -116,7 +185,8 @@ class AMQPListener(base.Listener):
message,
unique_id,
ctxt.msg_id,
ctxt.reply_q))
ctxt.reply_q,
self._obsolete_reply_queues))
def poll(self, timeout=None):
while not self._stopped.is_set():

11
oslo_messaging/_drivers/impl_rabbit.py

@ -1081,8 +1081,17 @@ class Connection(object):
"retrying...") % {
'exchange': exchange.name,
'routing_key': routing_key})
time.sleep(1)
time.sleep(0.25)
continue
elif exc.code == 404:
msg = _("The exchange %(exchange)s to send to "
"%(routing_key)s still doesn't exist after "
"%(duration)s sec abandonning...") % {
'duration': duration,
'exchange': exchange.name,
'routing_key': routing_key}
LOG.info(msg)
raise rpc_amqp.AMQPDestinationNotFound(msg)
raise
def direct_send(self, msg_id, msg):

39
oslo_messaging/tests/drivers/test_impl_rabbit.py

@ -355,6 +355,11 @@ class TestSendReceive(test_utils.BaseTestCase):
('zero', dict(rx_id=False, reply=0)),
]
_reply_fail = [
('reply_success', dict(reply_failure_404=False)),
('reply_failure', dict(reply_failure_404=True)),
]
_failure = [
('success', dict(failure=False)),
('failure', dict(failure=True, expected=False)),
@ -376,11 +381,14 @@ class TestSendReceive(test_utils.BaseTestCase):
cls.scenarios = testscenarios.multiply_scenarios(cls._n_senders,
cls._context,
cls._reply,
cls._reply_fail,
cls._failure,
cls._timeout,
cls._reply_ending)
def test_send_receive(self):
self.config(kombu_reconnect_timeout=0.5,
group="oslo_messaging_rabbit")
self.config(heartbeat_timeout_threshold=0,
group="oslo_messaging_rabbit")
self.config(send_single_reply=self.send_single_reply,
@ -409,16 +417,21 @@ class TestSendReceive(test_utils.BaseTestCase):
def send_and_wait_for_reply(i):
try:
if self.reply_failure_404:
timeout = 0.01
else:
timeout = self.timeout
replies.append(driver.send(target,
self.ctxt,
{'tx_id': i},
wait_for_reply=True,
timeout=self.timeout))
timeout=timeout))
self.assertFalse(self.failure)
self.assertIsNone(self.timeout)
except (ZeroDivisionError, oslo_messaging.MessagingTimeout) as e:
replies.append(e)
self.assertTrue(self.failure or self.timeout is not None)
self.assertTrue(self.failure or self.timeout is not None
or self.reply_failure_404)
while len(senders) < self.n_senders:
senders.append(threading.Thread(target=send_and_wait_for_reply,
@ -438,6 +451,18 @@ class TestSendReceive(test_utils.BaseTestCase):
if len(order) > 1:
order[-1], order[-2] = order[-2], order[-1]
if self.reply_failure_404:
start = time.time()
# NOTE(sileht): Simulate a rpc client restart
# By returning a ExchangeNotFound when we try to
# send reply
exc = (driver._reply_q_conn.connection.
connection.channel_errors[0]())
exc.code = 404
self.useFixture(mockpatch.Patch(
'kombu.messaging.Producer.publish',
side_effect=exc))
for i in order:
if self.timeout is None:
if self.failure:
@ -451,11 +476,19 @@ class TestSendReceive(test_utils.BaseTestCase):
msgs[i].reply({'rx_id': i})
else:
msgs[i].reply(self.reply)
elif self.reply_failure_404:
msgs[i].reply({})
senders[i].join()
if self.reply_failure_404:
# NOTE(sileht) all reply fail, first take
# kombu_reconnect_timeout seconds to fail
# next immediatly fail
self.assertAlmostEqual(0.5, time.time() - start, 1)
self.assertEqual(len(senders), len(replies))
for i, reply in enumerate(replies):
if self.timeout is not None:
if self.timeout is not None or self.reply_failure_404:
self.assertIsInstance(reply, oslo_messaging.MessagingTimeout)
elif self.failure:
self.assertIsInstance(reply, ZeroDivisionError)

1
requirements.txt

@ -13,6 +13,7 @@ stevedore>=1.5.0 # Apache-2.0
# for jsonutils
six>=1.9.0
cachetools>=1.0.0 # MIT License
# FIXME(markmc): remove this when the drivers no longer
# import eventlet