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.. Copyright 2010-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0
International License (the "License"). You may not use this file except in compliance with the
License. A copy of the License is located at http://creativecommons.org/licenses/by-nc-sa/4.0/.
This file 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.
.. _aws-boto3-sqs-long-polling:
###################################
Enabling long polling in Amazon SQS
###################################
This Python example shows you how to enable long polling in Amazon SQS in one of these ways:
* For a newly created queue
* For an existing queue
* Upon receipt of a message
The scenario
============
Long polling reduces the number of empty responses by allowing Amazon SQS to wait a specified time
for a message to become available in the queue before sending a response. Also, long polling eliminates
false empty responses by querying all of the servers instead of a sampling of servers. To enable long
polling, you must specify a non-zero wait time for received messages. You can do this by setting the
:code:`ReceiveMessageWaitTimeSeconds` parameter of a queue or by setting the :code:`WaitTimeSeconds`
parameter on a message when it is received.
In these examples, the AWS SDK for Python is used to enable long polling
using the following Amazon SQS methods.
* `create_queue <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sqs.html#SQS.Client.create_queue>`_
* `set_queue_attributes <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sqs.html#SQS.Client.set_queue_attributes>`_.
* `receive_message <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sqs.html#SQS.Client.receive_message>`_.
For more information, see
`Amazon SQS Long Polling <http://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-long-polling.html>`_
in the *Amazon Simple Queue Service Developer Guide*.
Enable long polling when creating a queue
=========================================
The example below shows how to:
* Create a queue and enable long polling using
`create_queue <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sqs.html#SQS.Client.create_queue>`_.
Example
-------
.. code-block:: python
import boto3
# Create SQS client
sqs = boto3.client('sqs')
# Create a SQS queue with long polling enabled
response = sqs.create_queue(
QueueName='SQS_QUEUE_NAME',
Attributes={'ReceiveMessageWaitTimeSeconds': '20'}
)
print(response['QueueUrl'])
Enable long polling on an existing queue
========================================
The example below shows how to:
* Enable long polling on an existing queue using
`set_queue_attributes <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sqs.html#SQS.Client.set_queue_attributes>`_.
Example
-------
.. code-block:: python
import boto3
# Create SQS client
sqs = boto3.client('sqs')
queue_url = 'SQS_QUEUE_URL'
# Enable long polling on an existing SQS queue
sqs.set_queue_attributes(
QueueUrl=queue_url,
Attributes={'ReceiveMessageWaitTimeSeconds': '20'}
)
Enable long polling on message receipt
======================================
The example below shows how to:
* Enable long polling for a message on an SQS queue using
`receive_message <https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/sqs.html#SQS.Client.receive_message>`_.
Example
-------
.. code-block:: python
import boto3
# Create SQS client
sqs = boto3.client('sqs')
queue_url = 'SQS_QUEUE_URL'
# Long poll for message on provided SQS queue
response = sqs.receive_message(
QueueUrl=queue_url,
AttributeNames=[
'SentTimestamp'
],
MaxNumberOfMessages=1,
MessageAttributeNames=[
'All'
],
WaitTimeSeconds=20
)
print(response)
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