Enhanced step debugging with Amazon EMR - Amazon EMR
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Enhanced step debugging with Amazon EMR

If an Amazon EMR step fails and you submitted your work using the Step API operation with an AMI of version 5.x or later, Amazon EMR can identify and return the root cause of the step failure in some cases, along with the name of the relevant log file and a portion of the application stack trace via API. For example, the following failures can be identified:

  • A common Hadoop error such as the output directory already exists, the input directory does not exist, or an application runs out of memory.

  • Java errors such as an application that was compiled with an incompatible version of Java or run with a main class that is not found.

  • An issue accessing objects stored in Amazon S3.

This information is available using the DescribeStep and ListSteps API operations. The FailureDetails field of the StepSummary returned by those operations. To access the FailureDetails information, use the Amazon CLI, console, or Amazon SDK.

Console

The new Amazon EMR console doesn't offer step debugging. However, you can view cluster termination details with the following steps.

To view failure details with the console

  1. Sign in to the Amazon Web Services Management Console, and open the Amazon EMR console at https://console.amazonaws.cn/emr.

  2. Under EMR on EC2 in the left navigation pane, choose Clusters, and then select the cluster that you want to view.

  3. Note the Status value in the Summary section of the cluster details page. If the status is Terminated with errors, hover over the text to view cluster failure details.

CLI
To view failure details with the Amazon CLI

  • To get failure details for a step with the Amazon CLI, use the describe-step command.

    aws emr describe-step --cluster-id j-1K48XXXXXHCB --step-id s-3QM0XXXXXM1W

    The output will look similar to the following:

    {
  "Step": {
    "Status": {
      "FailureDetails": {
        "LogFile": "s3://amzn-s3-demo-bucket/logs/j-1K48XXXXXHCB/steps/s-3QM0XXXXXM1W/stderr.gz",
        "Message": "org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory s3://amzn-s3-demo-bucket/logs/beta already exists",
        "Reason": "Output directory already exists."
      },
      "Timeline": {
        "EndDateTime": 1469034209.143,
        "CreationDateTime": 1469033847.105,
        "StartDateTime": 1469034202.881
      },
      "State": "FAILED",
      "StateChangeReason": {}
    },
    "Config": {
      "Args": [
        "wordcount",
        "s3://amzn-s3-demo-bucket/input/input.txt",
        "s3://amzn-s3-demo-bucket/logs/beta"
      ],
      "Jar": "s3://amzn-s3-demo-bucket/jars/hadoop-mapreduce-examples-2.7.2-amzn-1.jar",
      "Properties": {}
    },
    "Id": "s-3QM0XXXXXM1W",
    "ActionOnFailure": "CONTINUE",
    "Name": "ExampleJob"
  }
}