This threadsafe callback request mechanism may also be used to delegate _connection.AsyncioConnection’s I/O loop exposes _connection.TornadoConnection’s I/O loop has ForĮxample, pika.SelectConnection’s I/O loop provides Native API for requesting an I/O loop-bound callback from another thread.
Pika.SelectConnection, you use the underlying asynchronous framework’s When using a non-blocking connection adapter, such as partial ( ack_message, channel, delivery_tag )) This method’s docstring for additional information. Pika.BlockingConnection abstracts its I/O loop from the application and To be executed in the connection adapter’s I/O loop thread using an
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The code running in the other thread may request the ack_message() function basic_ack ( delivery_tag ) else : # Channel is already closed, so we can't acknowledge this message # log and/or do something that makes sense for your app in this case. The message being acknowledged was retrieved (AMQP protocol constraint). Like this: def ack_message ( channel, delivery_tag ): """Note that `channel` must be the same Pika channel instance via which For example, the callback function’s implementation might look This isĪccomplished by requesting a callback to be executed in the adapter’s Single thread, which is the thread running the adapter’s I/O loop. Thread, since all accesses to the connection adapter instance must be from a Messages processed in another thread may not be acknowledged directly from that Loop’s message pump, permitting AMQP heartbeats and other I/O to be serviced in Thread, while the connection adapter’s thread continues to service its I/O AĬommon solution is to delegate processing of the incoming messages to another Timeout in consumers that take a long time to process an incoming message. Instance may result in a dropped AMQP/stream connection due to AMQP heartbeat The single-threaded usage constraint of an individual Pika connection adapter Requesting message acknowledgements from another thread _connection.AsyncioConnection, you can request aĬonnection using multiple connection parameter instances via the connectionĪdapter’s create_connection() class method. With non-blocking adapters, such as pika.SelectConnection and ConnectionParameters ( host = '', connection_attempts = 5, retry_delay = 1 )) connection = pika. ConnectionParameters ( host = '' ), pika. Retries occur after connection attempts using all of the given connection Needed in the last pika.ConnectionParameters element of the sequence. To enable retries, set connection_attempts and retry_delay as You can also pass multiple pika.ConnectionParameters instances forįault-tolerance as in the code snippet below (host names are just examples, ofĬourse). _connection.TwistedProtocolConnection - asynchronous _connection.TornadoConnection - asynchronous adapter _connection.GeventConnection - asynchronous adapter Pika.SelectConnection - asynchronous adapter without third-party Pika.BlockingConnection - synchronous adapter on top of library for _connection.AsyncioConnection - asynchronous adapter close () Pika provides the following adapters cancel () print ( 'Requeued %i messages' % requeued_messages ) connection. delivery_tag = 10 : break # Cancel the consumer and return any pending messages requeued_messages = channel. delivery_tag ) # Escape out of the loop after 10 messages if method_frame. consume ( 'test' ): # Display the message parts and acknowledge the message print ( method_frame, properties, body ) channel. channel () for method_frame, properties, body in channel. BlockingConnection () channel = connection. close ()Īnd an example of writing a blocking consumer: import pika connection = pika.
basic_publish ( exchange = 'test', routing_key = 'test', body = b 'Test message.' ) connection. Pika.BlockingConnection adapter: import pika connection = pika. Here is the most simple example of use, sending a message with the Pika tries to stay compatible with all of these, and to makeĪdapting it to a new environment as simple as possible. Wide variety of ways of getting network events to and from a PythonĪpplication. People may be using direct sockets, plain old select(), or any of the An instance of Pika’sīuilt-in connection adapters isn’t thread-safe, however. Greenlets, callbacks, continuations, and generators. Pika core takes care not to forbid them, either. Since threads aren’t appropriate to every situation, it doesn’t require Supports Python 3.4+ ( 1.1.0 was the last version to support 2.7) Pika is a pure-Python implementation of the AMQP 0-9-1 protocol including Pika is a RabbitMQ (AMQP 0-9-1) client library for Python.
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