Collecting a Trace for Turbopack Performance Auditing

To collect a trace file for Turbopack build performance auditing, follow these steps:

Generate a Trace File

1. Make sure you have the latest version of Next.js installed
2. Run your development server with the tracing environment variable 3:

Or if you're using yarn:

3. Navigate around your application or make edits to files to reproduce any performance issues you're experiencing 3
4. Stop the Next.js development server
5. A file called trace-turbopack will be generated in the .next folder 3

Analyzing the Trace

To analyze the trace file:

1. Use the built-in trace viewer command 3:

On older versions of Next.js, you might need to use:

2. Once the trace server is running, you can view the trace at https://trace.nextjs.org/ 3
3. By default, the trace viewer will aggregate timings. To see each individual time, switch from "Aggregated in order" to "Spans in order" at the top right of the viewer 3

What's in the Trace?

The trace file contains valuable information without including your application code 2:

• File paths
• Compilation times for each file
• Timings for individual transforms
• Memory allocation, deallocation, and persistence across functions 2

This advanced tracing gives the Next.js team all the information needed to investigate slowdowns and memory usage deeply 2.

Sharing the Trace

When reporting issues related to Turbopack performance and memory usage, please include the trace file in your GitHub issue 1. This helps the Next.js team investigate and improve performance metrics.