Each of the numeric metric data for an entity (CPU of a host, heap used in a VM…) can have a threshold value set. Threshold is evaluated against the metric data points received, usually every 5 seconds. The metric with a threshold set will have one of the following status levels: Green, Yellow and Red. The entity’s status is derived from all its metric statuses according to worst-child rules (if any metric for the entity is red, the entity is red).
As long as the metric value does not exceed the threshold the status remains Green. If 3 or more metric data points are beyond the threshold the status turns to Yellow. If the average metric value within the last 5 minutes is beyond the threshold the status becomes Red. Once the 5 minute average goes below the threshold the status becomes Green again. Note that Diagnostics status does not revert to Yellow it goes directly back to Green.
The threshold values for metrics are configurable in the UI (details pane) and some metrics also have default thresholds set. The default threshold configuration is set in the server’s etc directory in thresholds.configuration.
If you need to set thresholds on specific methods you would want to add a separate entry in the points file for each method and this will allow you to set up thresholds and alerts for the specific method.