Metric Grouping Issue (MGI) Troubleshooting Framework APM

Metric Grouping Issues are often described as having “too many metric names’’. When the same metrics and transactions are given different names, their average time is diluted and the APM dashboard misrepresents the performance and bottlenecks of the application. Additionally, this can overwhelm the dashboard insights making it difficult to identify problem spots. If you’ve recently seen a sudden drop in the amount of metrics you’re used to seeing, or if you’re seeing no metrics at all, it is possible that your application may have an MGI clamp on it. When this happens, it puts extra stress on the APM agent as well as the new relic collector, that can cause slow down and inaccurate data.

When New Relic recognizes that an application is experiencing MGIs, it will notify our system to apply a clamp to the agent. A clamp is a rule applied by New Relic that may limit or block data and new metrics from coming into the New Relic UI. This change in metric data can usually be seen on the APM dashboard for your application.

Most common changes are:

  • Reduced traces for a transaction
  • Reduced metric data
  • Gaps in data in the New Relic APM.

If you suspect that your application may have a metric clamp, you check for any clamps on the APM dashboard of the application.

To check if your application has a metric clamp:

  1. Go to the APM dashboard of your application.
  2. On the left sidebar, find the Metric Normalization tab.
  3. On the Metric Normalization tab, you will see a list of metric rules that have been applied to the application by the user or New Relic
  4. If your application has a metric clamp, you will see the rule, DENY_NEW_METRICS

This rule cannot be removed by the user. To remove the clamp from the application, the user will need to contact their account manager or submit a support ticket to New Relic. New Relic and the customer will have to reconfigure the instrumentation of the agent on the application to reduce the individual metric data coming into New Relic.

If a metric matches a deny-new-metrics rule expression it must exist in the metrics store or it will be renamed to Supportability/MetricExplosion/BlacklistedMetric. Essentially, you can set up an alert for Supportability/MetricExplosion/BlacklistedMetric to notify if your application has a Metric Grouping Issue occurring.

And as a final resort, if you are still unable to resolve the issue please reach out to New Relic Global Technical Support either by clicking the “?” in the New Relic One UI or going to support.newrelic.com. Please be sure to mention, in as much detail as possible, the steps you have tried already and details of what you expect to see and what you are seeing.

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