fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
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Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all \u003cpre\u003e\u003ccode\u003e blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks"); } } catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); } })(); (function(){ try { var __m = "github.com"; var __re = new RegExp('^' + "github\\.com" + '
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fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix"); } } catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length \u003e 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms"); } } catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links"); } } catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); } })(); (function(){ try { var __m = "youtube.com"; var __re = new RegExp('^' + "youtube\\.com" + '
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fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
Comment thread
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default"); } } catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers"); } } catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + '
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fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
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Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
View file
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Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode"); } } catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); } })(); })();
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fix(cloudflare): Use TransformStream to keep track of streams#20452

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Merged
JPeer264 merged 2 commits into from
Apr 22, 2026
Merged

fix(cloudflare): Use TransformStream to keep track of streams #20452

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55183ba
fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
339219a
fixup! fix(cloudflare): Use TransformStream to keep streams open
JPeer264 Apr 22, 2026
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54 changes: 25 additions & 29 deletions packages/cloudflare/src/request.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -129,40 +129,36 @@ export function wrapRequestHandler(
const classification = classifyResponseStreaming(res);

if (classification.isStreaming && res.body) {
// Streaming response detected - monitor consumption to keep span alive
try {
const [clientStream, monitorStream] = res.body.tee();

// Monitor stream consumption and end span when complete
const streamMonitor = (async () => {
const reader = monitorStream.getReader();

try {
let done = false;
while (!done) {
const result = await reader.read();
done = result.done;
}
} catch {
// Stream error or cancellation - will end span in finally
} finally {
reader.releaseLock();
span.end();
waitUntil?.(flushAndDispose(client));
}
})();

// Keep worker alive until stream monitoring completes (otherwise span won't end)
waitUntil?.(streamMonitor);

// Return response with client stream
return new Response(clientStream, {
let ended = false;

const endSpanOnce = (): void => {
if (ended) return;

ended = true;
span.end();
waitUntil?.(flushAndDispose(client));
};

const transform = new TransformStream({
flush() {
// Source stream completed normally.
endSpanOnce();
},
cancel() {
// Client disconnected (or downstream cancelled). The `cancel`
// is being called while the response is still considered
// active, so this is a safe place to end the span.
endSpanOnce();
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},
});
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return new Response(res.body.pipeThrough(transform), {
status: res.status,
statusText: res.statusText,
headers: res.headers,
});
} catch (_e) {
// tee() failed (e.g stream already locked) - fall back to non-streaming handling
} catch {
span.end();
waitUntil?.(flushAndDispose(client));
return res;
Expand Down
8 changes: 5 additions & 3 deletions packages/cloudflare/test/instrumentations/worker/instrumentFetch.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -163,9 +163,11 @@ describe('instrumentFetch', () => {
const wrappedHandler = withSentry(vi.fn(), handler);
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn(promise => waits.push(promise));
await wrappedHandler.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext);
await wrappedHandler
.fetch?.(new Request('https://example.com'), MOCK_ENV_WITHOUT_DSN, {
waitUntil,
} as unknown as ExecutionContext)
.then(response => response.text());
expect(flush).not.toBeCalled();
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
Expand Down
184 changes: 173 additions & 11 deletions packages/cloudflare/test/request.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ const MOCK_OPTIONS: CloudflareOptions = {
dsn: 'https://public@dsn.ingest.sentry.io/1337',
};

const NODE_MAJOR_VERSION = parseInt(process.versions.node.split('.')[0]!);

function addDelayedWaitUntil(context: ExecutionContext) {
context.waitUntil(new Promise<void>(resolve => setTimeout(() => resolve())));
}
Expand DownExpand Up@@ -44,7 +46,7 @@ describe('withSentry', () => {
await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response('test'),
);
).then(response => response.text());

expect(waitUntilSpy).toHaveBeenCalledTimes(1);
expect(waitUntilSpy).toHaveBeenLastCalledWith(expect.any(Promise));
Expand DownExpand Up@@ -111,11 +113,8 @@ describe('withSentry', () => {

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
addDelayedWaitUntil(context);
const response = new Response('test');
// Add Content-Length to skip probing
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());
expect(waitUntil).toBeCalled();
vi.advanceTimersToNextTimer().runAllTimers();
await Promise.all(waits);
Expand DownExpand Up@@ -336,7 +335,7 @@ describe('withSentry', () => {
SentryCore.captureMessage('sentry-trace');
return new Response('test');
},
);
).then(response => response.text());

// Wait for async span end and transaction capture
await new Promise(resolve => setTimeout(resolve, 50));
Expand DownExpand Up@@ -389,10 +388,8 @@ describe('flushAndDispose', () => {
const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);

await wrapRequestHandler({ options: MOCK_OPTIONS, request: new Request('https://example.com'), context }, () => {
const response = new Response('test');
response.headers.set('content-length', '4');
return response;
});
return new Response('test');
}).then(response => response.text());

// Wait for all waitUntil promises to resolve
await Promise.all(waits);
Expand DownExpand Up@@ -518,6 +515,171 @@ describe('flushAndDispose', () => {
disposeSpy.mockRestore();
});

// Regression tests for https://github.com/getsentry/sentry-javascript/issues/20409
//
// Pre-fix: streaming responses were observed via `body.tee()` + a long-running
// `waitUntil(streamMonitor)`. Cloudflare caps `waitUntil` at ~30s after the
// handler returns, so any stream taking longer than 30s to fully emit had the
// monitor cancelled before `span.end()` / `flushAndDispose()` ran — silently
// dropping the root `http.server` span.
//
// Post-fix: the body is piped through a passthrough `TransformStream`; the
// `flush` (normal completion) and `cancel` (client disconnect) callbacks fire
// while the response stream is still active (no waitUntil cap), so they can
// safely end the span and register `flushAndDispose` via a fresh `waitUntil`
// window. The contract guaranteed below: `waitUntil` is NOT called with any
// long-running stream-observation promise — only with `flushAndDispose`, and
// only after the response stream has finished (either by completion or cancel).
describe('regression #20409: streaming responses do not park stream observation in waitUntil', () => {
test('waitUntil is not called until streaming response is fully delivered', async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits chunk1, then waits indefinitely until we open the gate
// before emitting chunk2 + closing. Models a long-running upstream
// (e.g. SSE / LLM streaming) whose body takes longer than the
// handler-return time to fully drain.
let releaseLastChunk!: () => void;
const lastChunkGate = new Promise<void>(resolve => {
releaseLastChunk = resolve;
});

const stream = new ReadableStream({
async start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
await lastChunkGate;
controller.enqueue(new TextEncoder().encode('chunk2'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler has returned, but the source stream has NOT closed yet.
// The pre-fix code would have already enqueued a long-running
// `waitUntil(streamMonitor)` task at this point. The post-fix code
// must not call waitUntil at all here.
expect(waitUntil).not.toHaveBeenCalled();

// Drain the response — Cloudflare would do this when forwarding to the client.
const reader = result.body!.getReader();
await reader.read(); // chunk1
// Source still hasn't closed — still no waitUntil.
expect(waitUntil).not.toHaveBeenCalled();

releaseLastChunk();
await reader.read(); // chunk2
await reader.read(); // done
reader.releaseLock();

// Stream completed → TransformStream `flush` fired → span ended →
// `flushAndDispose(client)` queued via waitUntil exactly once.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();

flushSpy.mockRestore();
disposeSpy.mockRestore();
});

// Node 18's TransformStream does not invoke the transformer's `cancel` hook
// when the downstream consumer cancels (WHATWG spec addition landed in Node 20).
// Cloudflare Workers run modern V8 where this works, so we only skip the
// test under Node 18.
test.skipIf(NODE_MAJOR_VERSION < 20)(
'waitUntil is called once and dispose runs when client cancels mid-stream',
async () => {
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

// Stream emits one chunk and then never closes — models an upstream
// that keeps emitting indefinitely. We then cancel the response from
// the consumer side to model a client disconnect.
let sourceCancelled = false;
const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('chunk1'));
// intentionally don't close
},
cancel() {
sourceCancelled = true;
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

// Handler returned, source still open — no waitUntil yet.
expect(waitUntil).not.toHaveBeenCalled();

const reader = result.body!.getReader();
await reader.read(); // chunk1
await reader.cancel('client disconnected'); // simulates client disconnect
reader.releaseLock();

// TransformStream `cancel` fired → span ended → flushAndDispose queued.
await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);
expect(waitUntil).toHaveBeenLastCalledWith(expect.any(Promise));
expect(flushSpy).toHaveBeenCalled();
expect(disposeSpy).toHaveBeenCalled();
// pipeThrough should also propagate the cancel upstream to the source.
expect(sourceCancelled).toBe(true);

flushSpy.mockRestore();
disposeSpy.mockRestore();
},
);

test('waitUntil is called exactly once even if the response is consumed multiple times', async () => {
// Sanity: no matter how the response is drained, the TransformStream's
// flush callback must only end the span (and queue flushAndDispose) once.
const waits: Promise<unknown>[] = [];
const waitUntil = vi.fn((promise: Promise<unknown>) => waits.push(promise));
const context = { waitUntil } as unknown as ExecutionContext;

const flushSpy = vi.spyOn(SentryCore.Client.prototype, 'flush').mockResolvedValue(true);
const disposeSpy = vi.spyOn(CloudflareClient.prototype, 'dispose');

const stream = new ReadableStream({
start(controller) {
controller.enqueue(new TextEncoder().encode('a'));
controller.enqueue(new TextEncoder().encode('b'));
controller.close();
},
});

const result = await wrapRequestHandler(
{ options: MOCK_OPTIONS, request: new Request('https://example.com'), context },
() => new Response(stream, { headers: { 'content-type': 'text/event-stream' } }),
);

const text = await result.text();
expect(text).toBe('ab');

await Promise.all(waits);
expect(waitUntil).toHaveBeenCalledTimes(1);

flushSpy.mockRestore();
disposeSpy.mockRestore();
});
});

test('dispose is NOT called for protocol upgrade responses (status 101)', async () => {
const context = createMockExecutionContext();
const waits: Promise<unknown>[] = [];
Expand Down
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