Question

我正在使用Celery和Redis来运行一些后台任务，但每次调用一个任务时，它都会创建一个与Redis的新连接。我在Heroku上，我的Redis to Go计划允许10个连接。我很快达到了这个限制并且达到了“达到最大客户数”错误。

如何确保Celery在单个连接上排队任务而不是每次都打开一个新任务？

编辑 - 包括完整的追溯

File "/app/.heroku/venv/lib/python2.7/site-packages/django/core/handlers/base.py", line 111, in get_response
   response = callback(request, *callback_args, **callback_kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/newrelic-1.4.0.137/newrelic/api/object_wrapper.py", line 166, in __call__
   self._nr_instance, args, kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/newrelic-1.4.0.137/newrelic/hooks/framework_django.py", line 447, in wrapper
   return wrapped(*args, **kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 77, in wrapped_view
   return view_func(*args, **kwargs)

 File "/app/feedback/views.py", line 264, in zencoder_webhook_handler
   tasks.process_zencoder_notification.delay(webhook)

 File "/app/.heroku/venv/lib/python2.7/site-packages/celery/app/task.py", line 343, in delay
   return self.apply_async(args, kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/celery/app/task.py", line 458, in apply_async
   with app.producer_or_acquire(producer) as P:

 File "/usr/local/lib/python2.7/contextlib.py", line 17, in __enter__
   return self.gen.next()

 File "/app/.heroku/venv/lib/python2.7/site-packages/celery/app/base.py", line 247, in producer_or_acquire
   with self.amqp.producer_pool.acquire(block=True) as producer:

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/connection.py", line 705, in acquire
   R = self.prepare(R)

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/pools.py", line 54, in prepare
   p = p()

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/pools.py", line 45, in <lambda>
   return lambda: self.create_producer()

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/pools.py", line 42, in create_producer
   return self.Producer(self._acquire_connection())

 File "/app/.heroku/venv/lib/python2.7/site-packages/celery/app/amqp.py", line 160, in __init__
   super(TaskProducer, self).__init__(channel, exchange, *args, **kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/messaging.py", line 83, in __init__
   self.revive(self.channel)

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/messaging.py", line 174, in revive
   channel = self.channel = maybe_channel(channel)

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/connection.py", line 879, in maybe_channel
   return channel.default_channel

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/connection.py", line 617, in default_channel
   self.connection

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/connection.py", line 610, in connection
   self._connection = self._establish_connection()

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/connection.py", line 569, in _establish_connection
   conn = self.transport.establish_connection()

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/transport/virtual/__init__.py", line 722, in establish_connection
   self._avail_channels.append(self.create_channel(self))

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/transport/virtual/__init__.py", line 705, in create_channel
   channel = self.Channel(connection)

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/transport/redis.py", line 271, in __init__
   self.client.info()

 File "/app/.heroku/venv/lib/python2.7/site-packages/newrelic-1.4.0.137/newrelic/api/object_wrapper.py", line 166, in __call__
   self._nr_instance, args, kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/newrelic-1.4.0.137/newrelic/api/function_trace.py", line 81, in literal_wrapper
   return wrapped(*args, **kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/redis/client.py", line 344, in info
   return self.execute_command('INFO')

 File "/app/.heroku/venv/lib/python2.7/site-packages/kombu/transport/redis.py", line 536, in execute_command
   conn.send_command(*args)

 File "/app/.heroku/venv/lib/python2.7/site-packages/redis/connection.py", line 273, in send_command
   self.send_packed_command(self.pack_command(*args))

 File "/app/.heroku/venv/lib/python2.7/site-packages/redis/connection.py", line 256, in send_packed_command
   self.connect()

 File "/app/.heroku/venv/lib/python2.7/site-packages/newrelic-1.4.0.137/newrelic/api/object_wrapper.py", line 166, in __call__
   self._nr_instance, args, kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/newrelic-1.4.0.137/newrelic/api/function_trace.py", line 81, in literal_wrapper
   return wrapped(*args, **kwargs)

 File "/app/.heroku/venv/lib/python2.7/site-packages/redis/connection.py", line 207, in connect
   self.on_connect()

 File "/app/.heroku/venv/lib/python2.7/site-packages/redis/connection.py", line 233, in on_connect
   if self.read_response() != 'OK':

 File "/app/.heroku/venv/lib/python2.7/site-packages/redis/connection.py", line 283, in read_response
   raise response

ResponseError: max number of clients reached

Answer 1

我希望我使用的是Redis，因为有一个特定的选项来限制连接数：CELERY_REDIS_MAX_CONNECTIONS。

http://docs.celeryproject.org/en/3.0/configuration.html#celery-redis-max-connections（适用于3.0）
http://docs.celeryproject.org/en/latest/configuration.html#celery-redis-max-connections（适用于3.1）
http://docs.celeryproject.org/en/master/configuration.html#celery-redis-max-connections（适用于开发）

MongoDB具有类似的后端设置。

鉴于这些后端设置，我不知道BROKER_POOL_LIMIT实际上做了什么。希望CELERY_REDIS_MAX_CONNECTIONS解决您的问题。

我是其中一个使用CloudAMQP的人，而AMQP后端没有自己的连接限制参数。

Answer 2

我在使用CloudAMQP的Heroku上遇到了同样的问题。我不知道为什么，但在为BROKER_POOL_LIMIT设置分配低整数时我没有运气。

最终，我发现通过设置BROKER_POOL_LIMIT=None或BROKER_POOL_LIMIT=0，我的问题得到了缓解。根据Celery文档，这会禁用连接池。到目前为止，这对我来说并不是一个明显的问题，但是我不确定它是否适合你。

相关信息的链接：http://celery.readthedocs.org/en/latest/configuration.html#broker-pool-limit

Answer 3

尝试以下设置：

CELERY_IGNORE_RESULT = True
CELERY_STORE_ERRORS_EVEN_IF_IGNORED = True

Answer 4

我有一个类似的问题涉及连接数和Celery。它不是在Heroku上，而是Mongo而不是Redis。

我在任务模块级别的任务函数定义之外启动了连接。至少对于Mongo，这允许任务共享连接。

希望有所帮助。

https://github.com/instituteofdesign/wander/blob/master/wander/tasks.py

mongoengine.connect('stored_messages')

@celery.task(default_retry_delay = 61)
def pull(settings, google_settings, user, folder, messageid):
    '''
    Pulls a message from zimbra and stores it in Mongo
    '''

    try:
        imap = imap_connect(settings, user)
        imap.select(folder, True)
    .......

Celery为每个任务创建新连接

4 个答案: