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Short-lived streams (create, a few chunks, close) pay a fixed cost per stream that dominates once the per-chunk path is lean. Streams created internally (transform stream sides, tee branches, ReadableStream.from, transferred streams) were built by wrapper constructors that swapped the prototype of every instance and then assigned an own, enumerable `constructor` property to look like a public stream. Each internal stream therefore had its own hidden class and `Object.keys(stream)` reported `['constructor']`. The public constructors now accept the internal construction sentinel and leave controller setup to the caller, so every ReadableStream and WritableStream shares one hidden class and no per-instance prototype swap or own property is needed. The queue ring buffer grew after a push filled it, so the initial 8-slot ring held only three (value, size) pairs and a four-chunk stream reallocated every time. Growing before the push lets the ring hold four pairs. pipeTo observed the source's closed promise with two reactions and, on teardown, let the reader and writer release paths probe and reject promise records that only the pipe could have observed. One reaction pair now watches the source, and finalize drops the records before release. Signed-off-by: Matteo Collina <[email protected]>
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Benchmark GHA (webstreams): https://github.com/nodejs/node/actions/runs/35198908305 Results
Benchmark results:
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #66052 +/- ##
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+ Coverage 90.24% 90.27% +0.03%
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Files 789 789
Lines 270613 271576 +963
Branches 51802 51851 +49
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- Misses 16870 16871 +1
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WPT already asserts the class of tee branches, ReadableStream.from() results and TransformStream sides, and test-webstreams-clone-unref.js covers transferred streams.
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Round 17 of the webstreams performance work (follows #65625). This one targets the fixed per-stream cost of short-lived streams (create, a few chunks, close), which dominates once the per-chunk path is lean.
stream: unify internal webstream construction
Streams created internally (transform stream sides, tee branches,
ReadableStream.from, transferred streams) were built by wrapper constructors that swapped the prototype of every instance and then assigned an own, enumerableconstructorproperty. Each internal stream had its own hidden class, andObject.keys(new TransformStream().readable)reported['constructor']. The public constructors now accept the internal construction sentinel and leave controller setup to the caller: one hidden class per stream type, no per-instance prototype swap, no own property. A test pins the observable part.stream: trim webstream setup and teardown work
pipeTowatched the source's closed promise with two reactions and, on teardown, let the reader and writer release paths probe and reject promise records only the pipe could observe. One reaction pair now watches the source, and finalize drops the records before release.Benchmarks
node benchmark/compare.js --runs 30 webstreams, all 43 rows; only the significant ones listed, everything else is within noise:The last row is untouched code and sits at the edge of its interval; with 43 rows one such
*is the expected false positive.The lifecycle benchmark drives its source through
pull()one chunk at a time. A source that enqueues its chunks fromstart()(the common "body already in memory" shape) gains more, because it also hits the queue growth and the batch path: create → 4×1KB → close measured at +16% (getReaderloop), +17% (pipeTo) and +20% (pipeThrough+pipeTo) on this machine, three interleaved runs each.Ordering is unchanged: a 28-scenario microtask-ordering stress (start variants, transform start/cancel/error interleavings, pipeTo shutdown paths, tee, byte streams) logs identically against
main, apart from the removedconstructorkey. WPT streams/compression/encoding and the webstreams parallel batch are green.AI generated, humanly reviewed.