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Performance Monitoring for Web Streams (Response API) #9633
Description
This was originally raised in #9626
We currently don't track the performance of web streams well. What does count as web streams? Basically everything that returns data in chunks (probably even normal http responses too):
- Websockets
- Server Sent Events
- Video streams
- etc.
In node we do this reasonably well because we hook into res.end() which generally marks the end of a Stream, however, we need to improve the WinterCG case with Response. The reader seems to have a done property on stream chunks that we could use to mark the end of the stream.
Activity
[-]Performance with Web Streams[/-][+]Performance Monitoring for Web Streams[/+][-]Performance Monitoring for Web Streams[/-][+]Performance Monitoring for Web Streams (fetch)[/+][-]Performance Monitoring for Web Streams (fetch)[/-][+]Performance Monitoring for Web Streams (`Response` API)[/+]mydea commentedon Oct 23, 2026
Streamed responses now keep the
http.serverspan open until the body finishes on Cloudflare (#24932), Bun (#25025), and Deno, andfetchStreamPerformanceIntegrationtracks streamed fetch bodies in the browser. Unifying the per-runtime implementations is tracked in #25577, so closing this one.