http2: add diagnostics channel 'http2.server.stream.start' #58449

RaisinTen · 2025-05-25T14:08:44Z

No description provided.

Signed-off-by: Darshan Sen <raisinten@gmail.com>

nodejs-github-bot · 2025-05-25T14:08:49Z

Review requested:

@nodejs/http2
@nodejs/net

codecov · 2025-05-25T14:57:17Z

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.22%. Comparing base (c3b580d) to head (434dbaf).
Report is 46 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #58449      +/-   ##
==========================================
+ Coverage   90.19%   90.22%   +0.03%     
==========================================
  Files         635      635              
  Lines      187255   187588     +333     
  Branches    36775    36836      +61     
==========================================
+ Hits       168896   169256     +360     
+ Misses      11137    11096      -41     
- Partials     7222     7236      +14

Files with missing lines	Coverage Δ
lib/internal/http2/core.js	`95.55% <100.00%> (+0.04%)`	⬆️

... and 59 files with indirect coverage changes

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Flarna · 2025-05-27T12:45:09Z

doc/api/diagnostics_channel.md

@@ -1246,6 +1246,13 @@ closing the stream can be retrieved using the `stream.rstCode` property.

 Emitted when a stream is created on the server.

+`http2.server.stream.start`


It seems this one comes always together with http2.server.stream.created. In one case there is a nextTick in between.

Which use case is solved by this extra event?

If the timing between created and start is important we should test the timing stays as expected.

The distinction between the two is that 'created' is for when the stream has just been created but 'start' is where the application starts using the stream. Here, 'start' gets called in the nextTick because that's where the pushStream callback gets invoked, where the user code can start using the push stream. I have added a test for the timings, PTAL @Flarna .

But they always come in pairs, sometimes with a nextTick inbetween, sometimes not.
But there is no case where a create is not immediately followed by a start right?

Yes, that's right. It could be useful to debug any performance issues that might be stemming from the blocking code that runs after pushStream() get called but before the callback is fired.

Signed-off-by: Darshan Sen <raisinten@gmail.com>

Flarna · 2025-05-28T10:14:20Z

test/parallel/test-diagnostics-channel-http2-server-stream-start.js

+  // Since ServerHttp2Stream is not exported from any module, this just checks
+  // if the stream is an instance of Duplex and the constructor name is
+  // 'ServerHttp2Stream'.
+  assert.ok(stream instanceof Duplex);


note that exposing internals makes it hard to ever move this out of experimental at some point in time in future.

ServerHttp2Stream is actually a part of the public API. It's just that this class is not exposed for direct use by application code, like new ServerHttp2Stream(), although users still can by accessing the .constructor property of one of these instances.

nodejs-github-bot · 2025-05-29T09:09:35Z

CI: https://ci.nodejs.org/job/node-test-pull-request/67180/

nodejs-github-bot · 2025-05-29T11:11:47Z

Landed in fd46569

Signed-off-by: Darshan Sen <raisinten@gmail.com> PR-URL: #58449 Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>

http2: add diagnostics channel 'http2.server.stream.start'

27ca47e

Signed-off-by: Darshan Sen <raisinten@gmail.com>

nodejs-github-bot added http2 needs-ci labels May 25, 2025

RaisinTen added the diagnostics_channel label May 25, 2025