From 331f6044b9ae1ae7988182e29d2faa7a27fbb2c7 Mon Sep 17 00:00:00 2001
From: Yael Hermon <yaelhe@wix.com>
Date: Mon, 10 Dec 2018 07:29:50 +0200
Subject: [PATCH] worker: drain messages from internal message port

When the worker thread exits, drain the messages also from the internal
message port so that the call to 'kDispose' will occur only after all
the messages from the worker were processed in the parent, so stdio
messages from the worker will be successfully pushed to their target
streams in the parent.

PR-URL: https://github.com/nodejs/node/pull/24932
Fixes: https://github.com/nodejs/node/issues/24636
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
---
 lib/internal/worker.js                        |  1 +
 .../test-worker-message-port-drain.js         | 41 +++++++++++++++++++
 2 files changed, 42 insertions(+)
 create mode 100644 test/parallel/test-worker-message-port-drain.js

diff --git a/lib/internal/worker.js b/lib/internal/worker.js
index 88580893cdc015..669a86bb23faef 100644
--- a/lib/internal/worker.js
+++ b/lib/internal/worker.js
@@ -317,6 +317,7 @@ class Worker extends EventEmitter {
   [kOnExit](code) {
     debug(`[${threadId}] hears end event for Worker ${this.threadId}`);
     MessagePortPrototype.drain.call(this[kPublicPort]);
+    MessagePortPrototype.drain.call(this[kPort]);
     this[kDispose]();
     this.emit('exit', code);
     this.removeAllListeners();
diff --git a/test/parallel/test-worker-message-port-drain.js b/test/parallel/test-worker-message-port-drain.js
new file mode 100644
index 00000000000000..4fcb3da25e3f14
--- /dev/null
+++ b/test/parallel/test-worker-message-port-drain.js
@@ -0,0 +1,41 @@
+// Flags: --experimental-worker
+'use strict';
+require('../common');
+
+// This test ensures that the messages from the internal
+// message port are drained before the call to 'kDispose',
+// and so all the stdio messages from the worker are processed
+// in the parent and are pushed to their target streams.
+
+const assert = require('assert');
+const {
+  Worker,
+  isMainThread,
+  parentPort,
+  threadId,
+} = require('worker_threads');
+
+if (isMainThread) {
+  const workerIdsToOutput = new Map();
+
+  for (let i = 0; i < 2; i++) {
+    const worker = new Worker(__filename, { stdout: true });
+    const workerOutput = [];
+    workerIdsToOutput.set(worker.threadId, workerOutput);
+    worker.on('message', console.log);
+    worker.stdout.on('data', (chunk) => {
+      workerOutput.push(chunk.toString().trim());
+    });
+  }
+
+  process.on('exit', () => {
+    for (const [threadId, workerOutput] of workerIdsToOutput) {
+      assert.ok(workerOutput.includes(`1 threadId: ${threadId}`));
+      assert.ok(workerOutput.includes(`2 threadId: ${threadId}`));
+    }
+  });
+} else {
+  console.log(`1 threadId: ${threadId}`);
+  console.log(`2 threadId: ${threadId}`);
+  parentPort.postMessage(Array(100).fill(1));
+}