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[WIP] feat: Span Streaming POC#17852

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[WIP] feat: Span Streaming POC#17852
Lms24 wants to merge 84 commits intodevelopfrom
lms/feat-span-streaming-poc

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@Lms24 Lms24 commented Oct 2, 2025 •
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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', // <-- (not mandatory; integration is enough)
  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.

@Lms24 Lms24 changed the title feat: Span Streaming POC [WIP] feat: Span Streaming POC Oct 2, 2025
@Lms24 Lms24 self-assigned this Oct 2, 2025
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 31db546 to 20590fe Compare October 2, 2025 14:59
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github-actions bot commented Oct 2, 2025 •
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size-limit report 📦

Path Size % Change Change
@sentry/browser 26.54 kB +3.83% +978 B 🔺
@sentry/browser - with treeshaking flags 25.01 kB +3.88% +932 B 🔺
@sentry/browser (incl. Tracing) 43.8 kB +3.39% +1.44 kB 🔺
@sentry/browser (incl. Tracing, Profiling) 48.56 kB +3.25% +1.52 kB 🔺
@sentry/browser (incl. Tracing, Replay) 82.64 kB +1.81% +1.46 kB 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags 72.19 kB +1.97% +1.39 kB 🔺
@sentry/browser (incl. Tracing, Replay with Canvas) 87.31 kB +1.69% +1.45 kB 🔺
@sentry/browser (incl. Tracing, Replay, Feedback) 99.49 kB +1.49% +1.46 kB 🔺
@sentry/browser (incl. Feedback) 43.24 kB +2.26% +952 B 🔺
@sentry/browser (incl. sendFeedback) 31.2 kB +3.2% +967 B 🔺
@sentry/browser (incl. FeedbackAsync) 36.17 kB +2.68% +942 B 🔺
@sentry/browser (incl. Metrics) 27.51 kB +2.88% +769 B 🔺
@sentry/browser (incl. Logs) 27.66 kB +2.91% +780 B 🔺
@sentry/browser (incl. Metrics & Logs) 28.32 kB +2.77% +761 B 🔺
@sentry/react 28.28 kB +3.47% +947 B 🔺
@sentry/react (incl. Tracing) 46.1 kB +3.09% +1.38 kB 🔺
@sentry/vue 31.24 kB +4.1% +1.23 kB 🔺
@sentry/vue (incl. Tracing) 45.64 kB +3.24% +1.43 kB 🔺
@sentry/svelte 26.56 kB +3.84% +981 B 🔺
CDN Bundle 28.85 kB +2.63% +738 B 🔺
CDN Bundle (incl. Tracing) 45.69 kB +5.77% +2.49 kB 🔺
CDN Bundle (incl. Logs, Metrics) 29.7 kB +2.59% +749 B 🔺
CDN Bundle (incl. Tracing, Logs, Metrics) 46.52 kB +5.66% +2.49 kB 🔺
CDN Bundle (incl. Replay, Logs, Metrics) 68.81 kB +1.16% +788 B 🔺
CDN Bundle (incl. Tracing, Replay) 82.6 kB +3.16% +2.53 kB 🔺
CDN Bundle (incl. Tracing, Replay, Logs, Metrics) 83.48 kB +3.14% +2.54 kB 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) 88.06 kB +3% +2.56 kB 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) 88.92 kB +2.93% +2.52 kB 🔺
CDN Bundle - uncompressed 84.28 kB +2.51% +2.06 kB 🔺
CDN Bundle (incl. Tracing) - uncompressed 135.89 kB +6.23% +7.97 kB 🔺
⛔️ CDN Bundle (incl. Logs, Metrics) - uncompressed (max: null) 0 B removed removed
CDN Bundle (incl. Tracing, Logs, Metrics) - uncompressed 138.73 kB +6.1% +7.97 kB 🔺
CDN Bundle (incl. Replay, Logs, Metrics) - uncompressed 210.85 kB +1.03% +2.14 kB 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed 253 kB +3.35% +8.2 kB 🔺
CDN Bundle (incl. Tracing, Replay, Logs, Metrics) - uncompressed 255.82 kB +3.31% +8.2 kB 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed 265.81 kB +3.19% +8.2 kB 🔺
CDN Bundle (incl. Tracing, Replay, Feedback, Logs, Metrics) - uncompressed 268.62 kB +3.15% +8.2 kB 🔺
@sentry/nextjs (client) 48.53 kB +3.17% +1.49 kB 🔺
@sentry/sveltekit (client) 44.26 kB +3.39% +1.45 kB 🔺
@sentry/node-core 53 kB +1.63% +845 B 🔺
@sentry/node 169.37 kB +1.72% +2.86 kB 🔺
@sentry/node - without tracing 96.91 kB +3.16% +2.96 kB 🔺
@sentry/aws-serverless 112.15 kB +2.47% +2.69 kB 🔺

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github-actions bot commented Oct 2, 2025 •
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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 8,580 - 8,750 -2%
GET With Sentry 1,214 14% 1,591 -24%
GET With Sentry (error only) 5,804 68% 5,956 -3%
POST Baseline 1,152 - 1,155 -0%
POST With Sentry 477 41% 571 -16%
POST With Sentry (error only) 985 86% 1,036 -5%
MYSQL Baseline 3,159 - 3,207 -1%
MYSQL With Sentry 364 12% 463 -21%
MYSQL With Sentry (error only) 2,543 81% 2,577 -1%

View base workflow run

@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch 2 times, most recently from 84ec3fe to 4c1a555 Compare October 15, 2025 14:50
@Lms24 Lms24 mentioned this pull request Oct 15, 2025
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@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from dc5f6de to a2aec25 Compare October 16, 2025 12:06
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 7bb62f4 to fd533f3 Compare October 31, 2025 09:02
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch 2 times, most recently from a35edc7 to 2d9b938 Compare November 12, 2025 10:58
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from e8e3944 to 2049208 Compare November 12, 2025 16:21
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 2049208 to 860265a Compare November 19, 2025 16:43
@Lms24 Lms24 mentioned this pull request Nov 19, 2025
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@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 860265a to 41c93ff Compare November 21, 2025 14:34
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch 2 times, most recently from 23c46cd to 25b73c6 Compare November 25, 2025 12:53
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 66b37be to 282eed0 Compare December 11, 2025 14:34
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch 3 times, most recently from 50208b8 to 780b812 Compare December 18, 2025 08:50
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 2a75393 to 96f57a4 Compare January 9, 2026 13:12
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Lms24 commented Jan 15, 2026

For my own recollection:

  • branch lms/tmp-custom-tracer has a semi-working implementation for filtering spans via ignoreSpans on span start

@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 30d746d to 27b145d Compare January 19, 2026 09:02
@Lms24 Lms24 mentioned this pull request Jan 20, 2026
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@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from f528c45 to 577e487 Compare January 30, 2026 08:43
Lms24 and others added 22 commits February 13, 2026 09:53
@Lms24
remove redundant attribute serilaization functions
16f3871
@Lms24
spanStreamingIntegration everywhere
487004c
@Lms24
use SpanBuffer in browser
e84a9e7
@Lms24
fixups and failing node integration tests :)
e7f6429
@Lms24
add web vital support
679792b
@JPeer264 @Lms24
feat(test-utils): Add a way to wait for single spans for Span streami…
5ab0f52 
…ng (#18986)

How it should be used is in the JSDoc. It worked quite well for my
Cloudflare tests

Closes #18987 (added automatically)
@Lms24
web vitals wip
ffb524a
@Lms24
add plan for step-by-step migration
bd0bfb1
@Lms24
docs: Mark PR 1 as completed in span streaming plan
a398126
@Lms24
skip failing WIP tests to get an alpha out
47ae0f1
@Lms24
fix some more tests
b398a6e
@Lms24
size limit, skip tests, fix things
4cb67de
@Lms24
fix cls unit tests
8da6036
@Lms24
weird formatting stuff ??
c4840f6
@Lms24
lint
754c828
@Lms24
fix unit tests
cd5f63e
@Lms24
fix integration tests
42fc7d8
@Lms24
fix e2e tests
ed10bc1
@Lms24
export spanstreamingIntegration from tracing cdn bundles
6fdc08d
@Lms24
more bundle index fiels
8d16cc2
@Lms24
fix tests now? please?
a428809
@Lms24
size limit once again :(
c7a3465
@Lms24 Lms24 force-pushed the lms/feat-span-streaming-poc branch from 7aa8018 to c7a3465 Compare February 13, 2026 08:57
@Lms24 Lms24 mentioned this pull request Feb 13, 2026
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