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stream: fix TransformStream race on cancel with pending write #62040

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Merged
nodejs-github-bot merged 4 commits into from
Mar 4, 2026
Merged

stream: fix TransformStream race on cancel with pending write #62040

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2449435
stream: fix TransformStream race on cancel with pending write
marcopiraccini Feb 28, 2026
398e700
linting fixup
marcopiraccini Feb 28, 2026
a84a506
test-fixup, use assert
marcopiraccini Mar 3, 2026
23c602d
test if undefined instead of typeof. use node:test and assert
marcopiraccini Mar 3, 2026
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stream: fix TransformStream race on cancel with pending write 
Signed-off-by: marcopiraccini <marco.piraccini@gmail.com>
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@marcopiraccini
marcopiraccini committed Feb 28, 2026
commit 2449435053b8eb4ab9d68ce76cddb1994cee74af
8 changes: 6 additions & 2 deletions lib/internal/webstreams/transformstream.js
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,6 @@ const {
const assert = require('internal/assert');

const kSkipThrow = Symbol('kSkipThrow');

const getNonWritablePropertyDescriptor = (value) => {
return {
__proto__: null,
Expand Down Expand Up @@ -524,7 +523,12 @@ function transformStreamDefaultControllerError(controller, error) {

async function transformStreamDefaultControllerPerformTransform(controller, chunk) {
try {
return await controller[kState].transformAlgorithm(chunk, controller);
const transformAlgorithm = controller[kState].transformAlgorithm;
if (typeof transformAlgorithm !== 'function') {
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// Algorithms were cleared by a concurrent cancel/abort/close.
return;
}
return await transformAlgorithm(chunk, controller);
} catch (error) {
transformStreamError(controller[kState].stream, error);
throw error;
Expand Down
54 changes: 54 additions & 0 deletions test/parallel/test-whatwg-transformstream-cancel-write-race.js
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@@ -0,0 +1,54 @@
'use strict';

const common = require('../common');
const { TransformStream } = require('stream/web');
const { setTimeout } = require('timers/promises');

// Test for https://github.com/nodejs/node/issues/62036
// A late write racing with reader.cancel() should not throw an internal "transformAlgorithm is not a function" TypeError.

Check failure on line 8 in test/parallel/test-whatwg-transformstream-cancel-write-race.js

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async function test() {
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const stream = new TransformStream({
transform(chunk, controller) {
controller.enqueue(chunk);
},
});

await setTimeout(0);

const reader = stream.readable.getReader();
const writer = stream.writable.getWriter();

// Release backpressure.
const pendingRead = reader.read();

// Simulate client disconnect / shutdown.
const pendingCancel = reader.cancel(new Error('client disconnected'));

// Late write racing with cancel.
const pendingLateWrite = writer.write('late-write');

const results = await Promise.allSettled([
pendingRead,
pendingCancel,
pendingLateWrite,
]);

// pendingRead should fulfill (with done:true or a value).
// pendingCancel should fulfill.
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// pendingLateWrite may reject, but must NOT reject with an internal
// TypeError about transformAlgorithm not being a function.
for (const result of results) {
if (result.status === 'rejected') {
const err = result.reason;
if (err instanceof TypeError &&
/transformAlgorithm is not a function/.test(err.message)) {
throw new Error(
'Internal implementation error leaked: ' + err.message
);
}
}
}
}

test().then(common.mustCall());
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