still fails sometimes

src/js/node/http.ts

@@ -1255,7 +1255,8 @@ function flushFirstWrite(self) {
   let firstWrite = self[firstWriteSymbol];
   // at this point, the user did not call end and we have not flushed the first write
   // we need to flush it now and behave like chunked encoding
-
+  const { promise: controllerPromise, resolve: resolveController } = $newPromiseCapability(GlobalPromise);
+  self[controllerSymbol] = controllerPromise;
   self._reply(
     new Response(
       new ReadableStream({
@@ -1264,6 +1265,8 @@ function flushFirstWrite(self) {
           self[controllerSymbol] = controller;
           if (firstWrite) controller.write(firstWrite);
           firstWrite = undefined;
+          resolveController(controller);
+
           if (!self[finishedSymbol]) {
             const { promise, resolve } = $newPromiseCapability(GlobalPromise);
             self[deferredSymbol] = resolve;
@@ -1286,8 +1289,7 @@ ServerResponse.prototype._write = function (chunk, encoding, callback) {
 
     // we still wanna to flush if the user await some time before writing again
     // keeping the first write is a good performance optimization
-    // process.nextTick(flushFirstWrite, this);
-    // flushFirstWrite(this);
+    setTimeout(flushFirstWrite, 1, this);
     return;
   }
 
@@ -1315,10 +1317,16 @@ ServerResponse.prototype._writev = function (chunks, callback) {
 
 function ensureReadableStreamController(run) {
   const thisController = this[controllerSymbol];
-  if (thisController) return run(thisController);
+  if (thisController) {
+    if (thisController.then) {
+      return thisController.then(run);
+    }
+    return run(thisController);
+  }
   this.headersSent = true;
   let firstWrite = this[firstWriteSymbol];
-  this[controllerSymbol] = undefined;
+  const { promise: controllerPromise, resolve: resolveController } = $newPromiseCapability(GlobalPromise);
+  this[controllerSymbol] = controllerPromise;
   this._reply(
     new Response(
       new ReadableStream({
@@ -1328,6 +1336,8 @@ function ensureReadableStreamController(run) {
           if (firstWrite) controller.write(firstWrite);
           firstWrite = undefined;
           run(controller);
+          resolveController(controller);
+
           if (!this[finishedSymbol]) {
             const { promise, resolve } = $newPromiseCapability(GlobalPromise);
             this[deferredSymbol] = resolve;