[Fizz] Avoid hanging when suspending after aborting while rendering

gnoff · gnoff · commit f1589a3d946c · 2025-08-12T15:43:59.000-07:00
This fixes an edge case where you abort the render while rendering a component that ends up Suspending. It technically only applied if you were deep enough to be inside `renderNode` and was not susceptible to hanging if the abort + suspending component was being tried inside retryRenderTask/retryReplaytask.

The fix is to preempt the thenable checks in renderNode and check if the request is aborting and if so just bubble up to the task handler.

The reason this hung before is a new task would get scheduled after we had aborted every other task (minus the currently rendering one). This led to a situation where the task count would not hit zero.
diff --git a/packages/react-dom/src/__tests__/ReactDOMFizzServer-test.js b/packages/react-dom/src/__tests__/ReactDOMFizzServer-test.js
@@ -94,9 +94,7 @@ describe('ReactDOMFizzServer', () => {
     ReactDOM = require('react-dom');
     ReactDOMClient = require('react-dom/client');
     ReactDOMFizzServer = require('react-dom/server');
-    if (__EXPERIMENTAL__) {
-      ReactDOMFizzStatic = require('react-dom/static');
-    }
+    ReactDOMFizzStatic = require('react-dom/static');
     Stream = require('stream');
     Suspense = React.Suspense;
     use = React.use;
@@ -10784,4 +10782,54 @@ Unfortunately that previous paragraph wasn't quite long enough so I'll continue
     // Instead we assert that we never emitted the fallback of the Suspense boundary around the body.
     expect(streamedContent).not.toContain(randomTag);
   });
+
+  it('should be able to Suspend after aborting in the same component without hanging the render', async () => {
+    const controller = new AbortController();
+
+    const promise1 = new Promise(() => {});
+    function AbortAndSuspend() {
+      controller.abort('boom');
+      return React.use(promise1);
+    }
+
+    function App() {
+      return (
+        <html>
+          <body>
+            <Suspense fallback="loading...">
+              {/*
+                The particular code path that was problematic required the Suspend to happen in renderNode
+                rather than retryRenderTask so we render the aborting function inside a host component
+                intentionally here
+              */}
+              <div>
+                <AbortAndSuspend />
+              </div>
+            </Suspense>
+          </body>
+        </html>
+      );
+    }
+
+    const errors = [];
+    await act(async () => {
+      const result = await ReactDOMFizzStatic.prerenderToNodeStream(<App />, {
+        signal: controller.signal,
+        onError(e) {
+          errors.push(e);
+        },
+      });
+
+      result.prelude.pipe(writable);
+    });
+
+    expect(errors).toEqual(['boom']);
+
+    expect(getVisibleChildren(document)).toEqual(
+      <html>
+        <head />
+        <body>loading...</body>
+      </html>,
+    );
+  });
 });
diff --git a/packages/react-server/src/ReactFizzServer.js b/packages/react-server/src/ReactFizzServer.js
@@ -4155,7 +4155,9 @@ function renderNode(
             getSuspendedThenable()
           : thrownValue;
 
-      if (typeof x === 'object' && x !== null) {
+      if (request.status === ABORTING) {
+        // We are aborting so we can just bubble up to the task by falling through
+      } else if (typeof x === 'object' && x !== null) {
         // $FlowFixMe[method-unbinding]
         if (typeof x.then === 'function') {
           const wakeable: Wakeable = (x: any);
@@ -4254,7 +4256,9 @@ function renderNode(
             getSuspendedThenable()
           : thrownValue;
 
-      if (typeof x === 'object' && x !== null) {
+      if (request.status === ABORTING) {
+        // We are aborting so we can just bubble up to the task by falling through
+      } else if (typeof x === 'object' && x !== null) {
         // $FlowFixMe[method-unbinding]
         if (typeof x.then === 'function') {
           const wakeable: Wakeable = (x: any);
