.. _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://docs.aws.amazon.com/boto3/latest/reference/services/sqs/client/create_queue.html>_
set_queue_attributes <https://docs.aws.amazon.com/boto3/latest/reference/services/sqs/client/set_queue_attributes.html>_.
receive_message <https://docs.aws.amazon.com/boto3/latest/reference/services/sqs/client/receive_message.html>_.

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://docs.aws.amazon.com/boto3/latest/reference/services/sqs/client/create_queue.html>_.

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://docs.aws.amazon.com/boto3/latest/reference/services/sqs/client/set_queue_attributes.html>_.

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://docs.aws.amazon.com/boto3/latest/reference/services/sqs/client/receive_message.html>_.

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)