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Amazon EMR
Amazon EMR Release Guide

Configure Consistency Notifications for CloudWatch and Amazon SQS

You can enable CloudWatch metrics and Amazon SQS messages in EMRFS for Amazon S3 eventual consistency issues.

CloudWatch

When CloudWatch metrics are enabled, a metric named Inconsistency is pushed each time a FileSystem API call fails due to Amazon S3 eventual consistency.

To view CloudWatch metrics for Amazon S3 eventual consistency issues

To view the Inconsistency metric in the CloudWatch console, select the EMRFS metrics and then select a JobFlowId/Metric Name pair. For example: j-162XXXXXXM2CU ListStatus, j-162XXXXXXM2CU GetFileStatus, and so on.

  1. Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

  2. In the Dashboard, in the Metrics section, choose EMRFS.

  3. In the Job Flow Metrics pane, select one or more JobFlowId/Metric Name pairs. A graphical representation of the metrics appears in the window below.

Amazon SQS

When Amazon SQS notifications are enabled, an Amazon SQS queue with the name EMRFS-Inconsistency-<jobFlowId> is created when EMRFS is initialized. Amazon SQS messages are pushed into the queue when a FileSystem API call fails due to Amazon S3 eventual consistency. The message contains information such as JobFlowId, API, a list of inconsistent paths, a stack trace, and so on. Messages can be read using the Amazon SQS console or using the EMRFS read-sqs command.

To manage Amazon SQS messages for Amazon S3 eventual consistency issues

Amazon SQS messages for Amazon S3 eventual consistency issues can be read using the EMRFS CLI. To read messages from an EMRFS Amazon SQS queue, type the read-sqs command and specify an output location on the master node's local file system for the resulting output file.

You can also delete an EMRFS Amazon SQS queue using the delete-sqs command.

  1. To read messages from an Amazon SQS queue, type the following command. Replace queuename with the name of the Amazon SQS queue that you configured and replace /path/filename with the path to the output file:

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    emrfs read-sqs -queue-name queuename -output-file /path/filename

    For example, to read and output Amazon SQS messages from the default queue, type:

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    emrfs read-sqs -queue-name EMRFS-Inconsistency-j-162XXXXXXM2CU -output-file /path/filename

    Note

    You can also use the -q and -o shortcuts instead of -queue-name and -output-file respectively.

  2. To delete an Amazon SQS queue, type the following command:

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    emrfs delete-sqs -queue-name queuename

    For example, to delete the default queue, type:

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    emrfs delete-sqs -queue-name EMRFS-Inconsistency-j-162XXXXXXM2CU

    Note

    You can also use the -q shortcut instead of -queue-name.