fix(process): drain Windows stdio before exit fallback settle

Author: obviyus

src/process/supervisor/adapters/child.test.ts

@@ -27,32 +27,12 @@ function createStubChild(pid = 1234) {
   Object.defineProperty(child, "killed", { value: false, configurable: true, writable: true });
   Object.defineProperty(child, "exitCode", { value: null, configurable: true, writable: true });
   Object.defineProperty(child, "signalCode", { value: null, configurable: true, writable: true });
-  let emittedClose = false;
-  let emittedExit = false;
-  let closedStreams = 0;
-  const maybeEmitCloseAfterStreamShutdown = () => {
-    if (emittedClose || !emittedExit || closedStreams < 2) {
-      return;
-    }
-    emittedClose = true;
-    child.emit("close", child.exitCode, child.signalCode);
-  };
-  child.stdout.on("close", () => {
-    closedStreams += 1;
-    maybeEmitCloseAfterStreamShutdown();
-  });
-  child.stderr.on("close", () => {
-    closedStreams += 1;
-    maybeEmitCloseAfterStreamShutdown();
-  });
   const killMock = vi.fn(() => true);
   child.kill = killMock as ChildProcess["kill"];
   const emitClose = (code: number | null, signal: NodeJS.Signals | null = null) => {
-    emittedClose = true;
     child.emit("close", code, signal);
   };
   const emitExit = (code: number | null, signal: NodeJS.Signals | null = null) => {
-    emittedExit = true;
     child.exitCode = code;
     child.signalCode = signal;
     child.emit("exit", code, signal);
@@ -197,7 +177,7 @@ describe("createChildAdapter", () => {
     vi.useFakeTimers();
     setPlatform("win32");
 
-    const { adapter, emitExit } = await (async () => {
+    const { adapter, emitExit, child } = await (async () => {
       const stub = createStubChild(8642);
       spawnWithFallbackMock.mockResolvedValue({
         child: stub.child,
@@ -216,6 +196,8 @@ describe("createChildAdapter", () => {
     });
 
     emitExit(0, null);
+    child.stdout?.emit("end");
+    child.stderr?.emit("end");
     await vi.advanceTimersByTimeAsync(300);
 
     expect(settled).toHaveBeenCalledWith({ code: 0, signal: null });

src/process/supervisor/adapters/child.ts

@@ -125,6 +125,8 @@ export async function createChildAdapter(params: {
   let forceKillWaitFallbackTimer: NodeJS.Timeout | null = null;
   let childExitState: { code: number | null; signal: NodeJS.Signals | null } | null = null;
   let windowsCloseFallbackTimer: NodeJS.Timeout | null = null;
+  let stdoutDrained = child.stdout == null;
+  let stderrDrained = child.stderr == null;
 
   const clearForceKillWaitFallback = () => {
     if (!forceKillWaitFallbackTimer) {
@@ -194,21 +196,46 @@ export async function createChildAdapter(params: {
     };
   };
 
+  const maybeSettleAfterWindowsExit = () => {
+    if (
+      process.platform !== "win32" ||
+      childExitState == null ||
+      !stdoutDrained ||
+      !stderrDrained
+    ) {
+      return;
+    }
+    settleWait(resolveObservedExitState(childExitState));
+  };
+
   const scheduleWindowsCloseFallback = () => {
     if (process.platform !== "win32") {
       return;
     }
     clearWindowsCloseFallbackTimer();
     windowsCloseFallbackTimer = setTimeout(() => {
-      if (waitResult || waitError !== undefined) {
-        return;
-      }
-      child.stdout?.destroy();
-      child.stderr?.destroy();
+      maybeSettleAfterWindowsExit();
     }, WINDOWS_CLOSE_STATE_SETTLE_TIMEOUT_MS);
     windowsCloseFallbackTimer.unref?.();
   };
 
+  child.stdout?.once("end", () => {
+    stdoutDrained = true;
+    maybeSettleAfterWindowsExit();
+  });
+  child.stdout?.once("close", () => {
+    stdoutDrained = true;
+    maybeSettleAfterWindowsExit();
+  });
+  child.stderr?.once("end", () => {
+    stderrDrained = true;
+    maybeSettleAfterWindowsExit();
+  });
+  child.stderr?.once("close", () => {
+    stderrDrained = true;
+    maybeSettleAfterWindowsExit();
+  });
+
   child.once("error", (error) => {
     rejectPendingWait(error);
   });