Enabling Long Polling for Amazon SQS Message Queues

Amazon SQS uses short polling by default, querying only a subset of the servers—​based on a weighted random distribution—​to determine whether any messages are available for inclusion in the response.

Long polling helps reduce your cost of using Amazon SQS by reducing the number of empty responses when there are no messages available to return in reply to a ReceiveMessage request sent to an Amazon SQS queue and eliminating false empty responses.

Note

You can set a long polling frequency from 1-20 seconds.

Enabling Long Polling when Creating a Queue

To enable long polling when creating an Amazon SQS queue, set the ReceiveMessageWaitTimeSeconds attribute on the CreateQueueRequest object before calling the AmazonSQS class' createQueue method.

Imports 

import com.amazonaws.services.sqs.AmazonSQS; import com.amazonaws.services.sqs.AmazonSQSClientBuilder; import com.amazonaws.services.sqs.model.AmazonSQSException; import com.amazonaws.services.sqs.model.CreateQueueRequest;

Code 

final AmazonSQS sqs = AmazonSQSClientBuilder.defaultClient(); // Enable long polling when creating a queue CreateQueueRequest create_request = new CreateQueueRequest() .withQueueName(queue_name) .addAttributesEntry("ReceiveMessageWaitTimeSeconds", "20"); try  sqs.createQueue(create_request); > catch (AmazonSQSException e)  if (!e.getErrorCode().equals("QueueAlreadyExists"))  throw e; > >

Enabling Long Polling on an Existing Queue

In addition to enabling long polling when creating a queue, you can also enable it on an existing queue by setting ReceiveMessageWaitTimeSeconds on the SetQueueAttributesRequest before calling the AmazonSQS class' setQueueAttributes method.

Imports 

import com.amazonaws.services.sqs.model.SetQueueAttributesRequest;

Code 

SetQueueAttributesRequest set_attrs_request = new SetQueueAttributesRequest() .withQueueUrl(queue_url) .addAttributesEntry("ReceiveMessageWaitTimeSeconds", "20"); sqs.setQueueAttributes(set_attrs_request);

Enabling Long Polling on Message Receipt

You can enable long polling when receiving a message by setting the wait time in seconds on the ReceiveMessageRequest that you supply to the AmazonSQS class' receiveMessage method.

Note

You should make sure that the AWS client’s request timeout is larger than the maximum long poll time (20s) so that your receiveMessage requests don’t time out while waiting for the next poll event!

Imports 

import com.amazonaws.services.sqs.model.ReceiveMessageRequest;

Code 

ReceiveMessageRequest receive_request = new ReceiveMessageRequest() .withQueueUrl(queue_url) .withWaitTimeSeconds(20); sqs.receiveMessage(receive_request);

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