oslo.messaging/oslo_messaging/_drivers/impl_kafka.py
Kirill Bespalov 162f6e987b Introduce TTL for idle connections
We can reduce a workload of rabbitmq through implementation
of expiration mechanism for idle connections in the pool with
next properties:

 conn_pool_ttl (default 20 min)
 conn_pool_min_size: the pool size limit for expire() (default 2)

The problem is timeless idle connections in the pool, which can be created
via some single huge workload of RPCServer. One SEND connection is heartbeat
thread + some network activity every n second. So, we can reduce it.

Here is two ways to implement an expiration:

 [1] Create a separated thread for checking expire date of connections
 [2] Make call expire() on pool.get() or pool.put()

The [1] has some threading overhead, but probably insignificant
because the thread can sleep 99% time and wake up every 20 mins (by default).
Anyway current implementation is [2].

Change-Id: Ie8781d10549a044656824ceb78b2fe2e4f7f8b43
2016-07-22 13:03:04 +03:00

379 lines
13 KiB
Python

# Copyright (C) 2015 Cisco Systems, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import threading
from oslo_messaging._drivers import base
from oslo_messaging._drivers import common as driver_common
from oslo_messaging._drivers import pool as driver_pool
from oslo_messaging._i18n import _LE
from oslo_messaging._i18n import _LW
from oslo_serialization import jsonutils
import kafka
from kafka.common import KafkaError
from oslo_config import cfg
from oslo_log import log as logging
LOG = logging.getLogger(__name__)
PURPOSE_SEND = 'send'
PURPOSE_LISTEN = 'listen'
kafka_opts = [
cfg.StrOpt('kafka_default_host', default='localhost',
deprecated_for_removal=True,
deprecated_reason="Replaced by [DEFAULT]/transport_url",
help='Default Kafka broker Host'),
cfg.PortOpt('kafka_default_port', default=9092,
deprecated_for_removal=True,
deprecated_reason="Replaced by [DEFAULT]/transport_url",
help='Default Kafka broker Port'),
cfg.IntOpt('kafka_max_fetch_bytes', default=1024 * 1024,
help='Max fetch bytes of Kafka consumer'),
cfg.IntOpt('kafka_consumer_timeout', default=1.0,
help='Default timeout(s) for Kafka consumers'),
cfg.IntOpt('pool_size', default=10,
help='Pool Size for Kafka Consumers'),
cfg.IntOpt('conn_pool_min_size', default=2,
help='The pool size limit for connections expiration policy'),
cfg.IntOpt('conn_pool_ttl', default=1200,
help='The time-to-live in sec of idle connections in the pool')
]
CONF = cfg.CONF
def pack_context_with_message(ctxt, msg):
"""Pack context into msg."""
if isinstance(ctxt, dict):
context_d = ctxt
else:
context_d = ctxt.to_dict()
return {'message': msg, 'context': context_d}
def target_to_topic(target, priority=None):
"""Convert target into topic string
:param target: Message destination target
:type target: oslo_messaging.Target
:param priority: Notification priority
:type priority: string
"""
if not priority:
return target.topic
return target.topic + '.' + priority
class Connection(object):
def __init__(self, conf, url, purpose):
driver_conf = conf.oslo_messaging_kafka
self.conf = conf
self.kafka_client = None
self.producer = None
self.consumer = None
self.fetch_messages_max_bytes = driver_conf.kafka_max_fetch_bytes
self.consumer_timeout = float(driver_conf.kafka_consumer_timeout)
self.url = url
self._parse_url()
# TODO(Support for manual/auto_commit functionality)
# When auto_commit is False, consumer can manually notify
# the completion of the subscription.
# Currently we don't support for non auto commit option
self.auto_commit = True
self._consume_loop_stopped = False
def _parse_url(self):
driver_conf = self.conf.oslo_messaging_kafka
self.hostaddrs = []
for host in self.url.hosts:
if host.hostname:
self.hostaddrs.append("%s:%s" % (
host.hostname,
host.port or driver_conf.kafka_default_port))
if not self.hostaddrs:
self.hostaddrs.append("%s:%s" % (driver_conf.kafka_default_host,
driver_conf.kafka_default_port))
def notify_send(self, topic, ctxt, msg, retry):
"""Send messages to Kafka broker.
:param topic: String of the topic
:param ctxt: context for the messages
:param msg: messages for publishing
:param retry: the number of retry
"""
message = pack_context_with_message(ctxt, msg)
self._ensure_connection()
self._send_and_retry(message, topic, retry)
def _send_and_retry(self, message, topic, retry):
current_retry = 0
if not isinstance(message, str):
message = jsonutils.dumps(message)
while message is not None:
try:
self._send(message, topic)
message = None
except Exception:
LOG.warning(_LW("Failed to publish a message of topic %s"),
topic)
current_retry += 1
if retry is not None and current_retry >= retry:
LOG.exception(_LE("Failed to retry to send data "
"with max retry times"))
message = None
def _send(self, message, topic):
self.producer.send_messages(topic, message)
def consume(self, timeout=None):
"""Receive up to 'max_fetch_messages' messages.
:param timeout: poll timeout in seconds
"""
duration = (self.consumer_timeout if timeout is None else timeout)
timer = driver_common.DecayingTimer(duration=duration)
timer.start()
def _raise_timeout():
LOG.debug('Timed out waiting for Kafka response')
raise driver_common.Timeout()
poll_timeout = (self.consumer_timeout if timeout is None
else min(timeout, self.consumer_timeout))
while True:
if self._consume_loop_stopped:
return
try:
next_timeout = poll_timeout * 1000.0
# TODO(use configure() method instead)
# Currently KafkaConsumer does not support for
# the case of updating only fetch_max_wait_ms parameter
self.consumer._config['fetch_max_wait_ms'] = next_timeout
messages = list(self.consumer.fetch_messages())
except Exception as e:
LOG.exception(_LE("Failed to consume messages: %s"), e)
messages = None
if not messages:
poll_timeout = timer.check_return(
_raise_timeout, maximum=self.consumer_timeout)
continue
return messages
def stop_consuming(self):
self._consume_loop_stopped = True
def reset(self):
"""Reset a connection so it can be used again."""
if self.consumer:
self.consumer.close()
self.consumer = None
def close(self):
if self.kafka_client:
self.kafka_client.close()
self.kafka_client = None
if self.producer:
self.producer.stop()
self.consumer = None
def commit(self):
"""Commit is used by subscribers belonging to the same group.
After subscribing messages, commit is called to prevent
the other subscribers which belong to the same group
from re-subscribing the same messages.
Currently self.auto_commit option is always True,
so we don't need to call this function.
"""
self.consumer.commit()
def _ensure_connection(self):
if self.kafka_client:
return
try:
self.kafka_client = kafka.KafkaClient(
self.hostaddrs)
self.producer = kafka.SimpleProducer(self.kafka_client)
except KafkaError as e:
LOG.exception(_LE("Kafka Connection is not available: %s"), e)
self.kafka_client = None
def declare_topic_consumer(self, topics, group=None):
self._ensure_connection()
for topic in topics:
self.kafka_client.ensure_topic_exists(topic)
self.consumer = kafka.KafkaConsumer(
*topics, group_id=group,
bootstrap_servers=self.hostaddrs,
fetch_message_max_bytes=self.fetch_messages_max_bytes)
self._consume_loop_stopped = False
class OsloKafkaMessage(base.RpcIncomingMessage):
def __init__(self, ctxt, message):
super(OsloKafkaMessage, self).__init__(ctxt, message)
def requeue(self):
LOG.warning(_LW("requeue is not supported"))
def reply(self, reply=None, failure=None):
LOG.warning(_LW("reply is not supported"))
class KafkaListener(base.PollStyleListener):
def __init__(self, conn):
super(KafkaListener, self).__init__()
self._stopped = threading.Event()
self.conn = conn
self.incoming_queue = []
@base.batch_poll_helper
def poll(self, timeout=None):
while not self._stopped.is_set():
if self.incoming_queue:
return self.incoming_queue.pop(0)
try:
messages = self.conn.consume(timeout=timeout)
for msg in messages:
message = msg.value
LOG.debug('poll got message : %s', message)
message = jsonutils.loads(message)
self.incoming_queue.append(OsloKafkaMessage(
ctxt=message['context'], message=message['message']))
except driver_common.Timeout:
return None
def stop(self):
self._stopped.set()
self.conn.stop_consuming()
def cleanup(self):
self.conn.close()
def commit(self):
# TODO(Support for manually/auto commit functionality)
# It's better to allow users to commit manually and support for
# self.auto_commit = False option. For now, this commit function
# is meaningless since user couldn't call this function and
# auto_commit option is always True.
self.conn.commit()
class KafkaDriver(base.BaseDriver):
"""Note: Current implementation of this driver is experimental.
We will have functional and/or integrated testing enabled for this driver.
"""
def __init__(self, conf, url, default_exchange=None,
allowed_remote_exmods=None):
opt_group = cfg.OptGroup(name='oslo_messaging_kafka',
title='Kafka driver options')
conf.register_group(opt_group)
conf.register_opts(kafka_opts, group=opt_group)
super(KafkaDriver, self).__init__(
conf, url, default_exchange, allowed_remote_exmods)
# the pool configuration properties
max_size = self.conf.oslo_messaging_kafka.pool_size
min_size = self.conf.oslo_messaging_kafka.conn_pool_min_size
ttl = self.conf.oslo_messaging_kafka.conn_pool_ttl
self.connection_pool = driver_pool.ConnectionPool(
self.conf, max_size, min_size, ttl,
self._url, Connection)
self.listeners = []
def cleanup(self):
for c in self.listeners:
c.close()
self.listeners = []
def send(self, target, ctxt, message, wait_for_reply=None, timeout=None,
retry=None):
raise NotImplementedError(
'The RPC implementation for Kafka is not implemented')
def send_notification(self, target, ctxt, message, version, retry=None):
"""Send notification to Kafka brokers
:param target: Message destination target
:type target: oslo_messaging.Target
:param ctxt: Message context
:type ctxt: dict
:param message: Message payload to pass
:type message: dict
:param version: Messaging API version (currently not used)
:type version: str
:param retry: an optional default kafka consumer retries configuration
None means to retry forever
0 means no retry
N means N retries
:type retry: int
"""
with self._get_connection(purpose=PURPOSE_SEND) as conn:
conn.notify_send(target_to_topic(target), ctxt, message, retry)
def listen(self, target):
raise NotImplementedError(
'The RPC implementation for Kafka is not implemented')
def listen_for_notifications(self, targets_and_priorities, pool,
batch_size, batch_timeout):
"""Listen to a specified list of targets on Kafka brokers
:param targets_and_priorities: List of pairs (target, priority)
priority is not used for kafka driver
target.exchange_target.topic is used as
a kafka topic
:type targets_and_priorities: list
:param pool: consumer group of Kafka consumers
:type pool: string
"""
conn = self._get_connection(purpose=PURPOSE_LISTEN)
topics = set()
for target, priority in targets_and_priorities:
topics.add(target_to_topic(target, priority))
conn.declare_topic_consumer(topics, pool)
listener = KafkaListener(conn)
return base.PollStyleListenerAdapter(listener, batch_size,
batch_timeout)
def _get_connection(self, purpose):
return driver_common.ConnectionContext(self.connection_pool, purpose)