[WIP] feat: Span Streaming POC

[Lms24]

This PR contains the POC span streaming implementation for browser SDKs.

Can be tested on @sentry/browser@10.21.0-alpha.1 and any higher-level SDKs.

To opt into span streaming, set:

Sentry.init({
  dsn: '...',
  tracesSampleRate: 1,
  traceLifecycle: 'stream', <-- 
  integrations: [
    Sentry.browserTracingIntegration();
    Sentry.spanStreamingIntegration(); <-- 
  ],

  // if you use beforeSendSpan, you have to opt into the new serialized span format:
  beforeSendSpan: withStreamSpan(serializedSpan => {
     // do something
     return serializedSpan
   }),
})

Also note that spans will no longer be sent to any event processors added via one if the *.addEventProcessor APIs. If you have any event processors, consider using beforeSendSpan or ignoreSpans.

[github-actions]

size-limit report 📦

Path	Size	% Change	Change
@sentry/browser	24.76 kB	+0.47%	+115 B 🔺
@sentry/browser - with treeshaking flags	23.27 kB	+0.54%	+124 B 🔺
@sentry/browser (incl. Tracing)	41.41 kB	+1.03%	+420 B 🔺
@sentry/browser (incl. Tracing, Replay)	79.69 kB	+0.51%	+398 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	69.4 kB	+0.62%	+421 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)	84.39 kB	+0.47%	+394 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)	96.61 kB	+0.48%	+455 B 🔺
@sentry/browser (incl. Feedback)	41.45 kB	+0.31%	+125 B 🔺
@sentry/browser (incl. sendFeedback)	29.42 kB	+0.41%	+120 B 🔺
@sentry/browser (incl. FeedbackAsync)	34.36 kB	+0.31%	+105 B 🔺
@sentry/react	26.45 kB	+0.4%	+104 B 🔺
@sentry/react (incl. Tracing)	43.41 kB	+0.98%	+419 B 🔺
@sentry/vue	29.53 kB	+1.37%	+399 B 🔺
@sentry/vue (incl. Tracing)	43.21 kB	+0.99%	+420 B 🔺
@sentry/svelte	24.77 kB	+0.46%	+112 B 🔺
CDN Bundle	27.05 kB	+0.43%	+114 B 🔺
CDN Bundle (incl. Tracing)	41.95 kB	+0.74%	+307 B 🔺
CDN Bundle (incl. Tracing, Replay)	78.2 kB	+0.4%	+306 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)	83.69 kB	+0.41%	+339 B 🔺
CDN Bundle - uncompressed	79.2 kB	+0.32%	+247 B 🔺
CDN Bundle (incl. Tracing) - uncompressed	124.76 kB	+1%	+1.23 kB 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed	239.77 kB	+0.52%	+1.23 kB 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	252.54 kB	+0.49%	+1.23 kB 🔺
@sentry/nextjs (client)	45.48 kB	+0.94%	+423 B 🔺
@sentry/sveltekit (client)	41.83 kB	+1.01%	+415 B 🔺
@sentry/node-core	50.93 kB	+0.29%	+147 B 🔺
@sentry/node	154.87 kB	+0.31%	+467 B 🔺
@sentry/node - without tracing	92.81 kB	+0.17%	+156 B 🔺
@sentry/aws-serverless	106.49 kB	+0.15%	+149 B 🔺
@sentry/browser (incl. Tracing with Span Streaming)	42.96 kB	added	added

View base workflow run

[github-actions]

node-overhead report 🧳

Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.

Scenario	Requests/s	% of Baseline	Prev. Requests/s	Change %
GET Baseline	8,853	-	9,344	-5%
GET With Sentry	1,422	16%	1,412	+1%
GET With Sentry (error only)	6,147	69%	6,130	+0%
POST Baseline	1,219	-	1,211	+1%
POST With Sentry	527	43%	509	+4%
POST With Sentry (error only)	1,062	87%	1,069	-1%
MYSQL Baseline	3,377	-	3,221	+5%
MYSQL With Sentry	467	14%	370	+26%
MYSQL With Sentry (error only)	2,726	81%	2,625	+4%

View base workflow run