When creating your FIFO queue, configure the visibility timeout based on the time it takes to process each queue message. That could use a lot of compute resources unnecessarily, and have other undesirable effects. In this case, if you leave the visibility timeout as the default, then a new consumer will start processing your queue message every 30 seconds. For example, you could be developing a system for an online media site, where each queue message is a video that needs transcoding into many different formats. Now imagine a scenario where the processing of a queue message takes a long time, even hours. The queue has a single message.Īn initial receive message request returns the messageĪnother receive message request within the visibility timeout returns no messagesĪfter waiting for the visibility timeout to expire, another receive message request returns the message again The following diagram shows how this works using a simple FIFO queue with the default visibility timeout. The default visibility timeout is 30 seconds. It configures how long after a message is received by one consumer will it be able to be received again by another. What if we want to be able to receive the same message again to retry processing which may have failed? That’s where the visibility timeout comes in. That was the case because all the messages had the same message group id, and SQS was maintaining message order. In fact 1 we saw that when we do multiple receive messages calls on an SQS FIFO queue only the first one returns a result. Moved automatically to a dead-letter queue after the configured maximum receivesĢ) If you don’t set the visibility timeout correctly, your message may be re-processed # Messages can be removed from the queue in these ways:ĭeleted automatically once the message retention period has expired While this is intended behaviour for a FIFO queue, remember that only once a message has been removed from the queue will the next message with the same message group id be returned. Messages that have the same messages group id will be returned in order. When sending messages to the queue, choose the message group id carefully. You can clearly see that the first receive message attempt returns Message 1, but the second attempt doesn’t return anything. "ReceiptHandle": "AQEBAbg4vEIbQ+OC/o7R/R5CmZMHv5cKcfzn7LCiKnm+u1p2jabE+Z9mm0b0/wpf+H3Qnh7BE/FtjErqifBMudHIFzpZhHcEy7wxvXuK1AhzpPhimnbIdM/BSmWLyOKADw+xmbngIoSNAlzeqHTIEuxOt9+5ULxki/JW6ar9SBnur6CHNGvzg34c4hblXKdBnlf34QWs/NS1rE8SZ6ErHTEvFBugz0aY7GaIQlLzaevZyXTnLkajLnU+9GZ+i/fcx0+qx+hGJQ9Hm4Ko66xTDGqdTg=", If you execute the script you’ll see this output. Deleting queue." aws sqs delete-queue -queue-url "$QUEUE_URL " QUEUE_URL = $(aws sqs create-queue -queue-name test.fifo -attributes FifoQueue =true,ContentBasedDeduplication =true -query QueueUrl -output text ) echo "Created SQS FIFO queue $QUEUE_URL " echo "Sending 3 messages to queue" aws sqs send-message -message-body "Message 1" -message-group-id 1 -queue-url "$QUEUE_URL " > /dev/nullĪws sqs send-message -message-body "Message 2" -message-group-id 1 -queue-url "$QUEUE_URL " > /dev/nullĪws sqs send-message -message-body "Message 3" -message-group-id 1 -queue-url "$QUEUE_URL " > /dev/nullĮcho "Receiving messages attempt 1" aws sqs receive-message -queue-url "$QUEUE_URL " echo "Receiving messages attempt 2" aws sqs receive-message -queue-url "$QUEUE_URL " echo "Finished. attempt to receive a message from the queue again. attempt to receive a message from the queue.send 3 messages to the queue, all with the same message group id.To demonstrate this, we’ll run a shell script which uses the AWS CLI to: If it’s received by a consumer, but for whatever reasons fails to process and isn’t deleted, then no other messages with the same message group id can be received. Imagine we have several messages on the queue with the same message group id. This is a way to group messages, so that messages within that group are always received in order. When you send a message to a FIFO queue a message group id must be provided. 1) If a message fails to be processed, it may block other messages # In this article you’ll discover the 3 most important caveats with SQS FIFO queues. That sounds great, but there are some other important features to understand to avoid unexpected queue behaviour. The first-in-first-out (FIFO) queue is the type of AWS SQS queue that guarantees order and provides exactly once delivery of messages.
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