Updated Node.js Language Metrics plugin

Change effective on 05 February 2024

We changed how Node.js Language Metrics are gathered by applications. We deprecated our native add-on for collecting these metrics in favor of a plugin that uses performance APIs built directly into Node.js.

If an app using Node.js >= 14.10.0 has Node.js Language Metrics enabled, this change takes effect on the next build and deploy.

The time series plots for Aggregate Time Spent in Garbage Collection, Aggregate Garbage Collections, Event Loop Latency, and Event Loop Usage can display some noticeable differences after this change takes effect for an app. These differences are expected as the Node.js performance APIs have more precision than our native add-on.

To use the deprecated native metrics plugin instead, set the config var HEROKU_LEGACY_NODE_PLUGIN to true and rebuild your app.