cluster: support windowsHide option for workers

Fixes: #17370

PR-URL: #17412
Fixes: #17370
Reviewed-By: Ben Noordhuis <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>
Reviewed-By: James M Snell <[email protected]>

doc/api/cluster.md

@@ -722,6 +722,8 @@ changes:
     This can be a number, or a function that takes no arguments and returns a
     number. By default each worker gets its own port, incremented from the
     master's `process.debugPort`.
+  * `windowsHide` {boolean} Hide the forked processes console window that would
+    normally be created on Windows systems. **Default:** `false`
 
 After calling `.setupMaster()` (or `.fork()`) this settings object will contain
 the settings, including the default values.

lib/internal/cluster/master.js

@@ -127,6 +127,7 @@ function createWorkerProcess(id, env) {
   return fork(cluster.settings.exec, cluster.settings.args, {
     env: workerEnv,
     silent: cluster.settings.silent,
+    windowsHide: cluster.settings.windowsHide,
     execArgv: execArgv,
     stdio: cluster.settings.stdio,
     gid: cluster.settings.gid,

test/parallel/test-cluster-fork-windowsHide.js

@@ -0,0 +1,76 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const child_process = require('child_process');
+const cluster = require('cluster');
+
+if (!process.argv[2]) {
+  /* It seems Windows only allocate new console window for
+   * attaching processes spawned by detached processes. i.e.
+   * - If process D is spawned by process C with `detached: true`,
+   *   and process W is spawned by process D with `detached: false`,
+   *   W will get a new black console window popped up.
+   * - If D is spawned by C with `detached: false` or W is spawned
+   *   by D with `detached: true`, no console window will pop up for W.
+   *
+   * So, we have to spawn a detached process first to run the actual test.
+   */
+  const master = child_process.spawn(
+    process.argv[0],
+    [process.argv[1], '--cluster'],
+    { detached: true, stdio: ['ignore', 'ignore', 'ignore', 'ipc'] });
+
+  const messageHandlers = {
+    workerOnline: common.mustCall((msg) => {
+    }),
+    mainWindowHandle: common.mustCall((msg) => {
+      assert.ok(/0\s*/.test(msg.value));
+    }),
+    workerExit: common.mustCall((msg) => {
+      assert.strictEqual(msg.code, 0);
+      assert.strictEqual(msg.signal, null);
+    })
+  };
+
+  master.on('message', (msg) => {
+    const handler = messageHandlers[msg.type];
+    assert.ok(handler);
+    handler(msg);
+  });
+
+  master.on('exit', common.mustCall((code, signal) => {
+    assert.strictEqual(code, 0);
+    assert.strictEqual(signal, null);
+  }));
+
+} else if (cluster.isMaster) {
+  cluster.setupMaster({
+    silient: true,
+    windowsHide: true
+  });
+
+  const worker = cluster.fork();
+  worker.on('exit', (code, signal) => {
+    process.send({ type: 'workerExit', code: code, signal: signal });
+  });
+
+  worker.on('online', (msg) => {
+    process.send({ type: 'workerOnline' });
+
+    let output = '0';
+    if (process.platform === 'win32') {
+      output = child_process.execSync(
+        'powershell -NoProfile -c ' +
+        `"(Get-Process -Id ${worker.process.pid}).MainWindowHandle"`,
+        { windowsHide: true, encoding: 'utf8' });
+    }
+
+    process.send({ type: 'mainWindowHandle', value: output });
+    worker.send('shutdown');
+  });
+
+} else {
+  cluster.worker.on('message', (msg) => {
+    cluster.worker.disconnect();
+  });
+}