From e05c29db3fdacdf843cae43fd9e96ba566c9ca87 Mon Sep 17 00:00:00 2001
From: Santiago Gimeno <santiago.gimeno@gmail.com>
Date: Wed, 1 Apr 2020 14:22:07 +0200
Subject: [PATCH] cluster: fix error on worker disconnect/destroy

Avoid sending multiple `exitedAfterDisconnect` messages when
concurrently calling `disconnect()` and/or `destroy()` from the worker
so `ERR_IPC_DISCONNECTED` errors are not generated.

Fixes: https://github.com/nodejs/node/issues/32106

PR-URL: https://github.com/nodejs/node/pull/32793
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
---
 lib/internal/cluster/child.js                 | 11 ++++-
 .../test-cluster-concurrent-disconnect.js     | 48 +++++++++++++++++++
 2 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 test/parallel/test-cluster-concurrent-disconnect.js

diff --git a/lib/internal/cluster/child.js b/lib/internal/cluster/child.js
index 250a82ecabaa34..74f30c0d2ece90 100644
--- a/lib/internal/cluster/child.js
+++ b/lib/internal/cluster/child.js
@@ -228,16 +228,23 @@ function _disconnect(masterInitiated) {
 
 // Extend generic Worker with methods specific to worker processes.
 Worker.prototype.disconnect = function() {
-  _disconnect.call(this);
+  if (![ 'disconnecting', 'destroying' ].includes(this.state)) {
+    this.state = 'disconnecting';
+    _disconnect.call(this);
+  }
+
   return this;
 };
 
 Worker.prototype.destroy = function() {
-  this.exitedAfterDisconnect = true;
+  if (this.state === 'destroying')
+    return;
 
+  this.exitedAfterDisconnect = true;
   if (!this.isConnected()) {
     process.exit(0);
   } else {
+    this.state = 'destroying';
     send({ act: 'exitedAfterDisconnect' }, () => process.disconnect());
     process.once('disconnect', () => process.exit(0));
   }
diff --git a/test/parallel/test-cluster-concurrent-disconnect.js b/test/parallel/test-cluster-concurrent-disconnect.js
new file mode 100644
index 00000000000000..22f72040263027
--- /dev/null
+++ b/test/parallel/test-cluster-concurrent-disconnect.js
@@ -0,0 +1,48 @@
+'use strict';
+
+// Ref: https://github.com/nodejs/node/issues/32106
+
+const common = require('../common');
+
+const assert = require('assert');
+const cluster = require('cluster');
+const os = require('os');
+
+if (cluster.isMaster) {
+  const workers = [];
+  const numCPUs = os.cpus().length;
+  let waitOnline = numCPUs;
+  for (let i = 0; i < numCPUs; i++) {
+    const worker = cluster.fork();
+    workers[i] = worker;
+    worker.once('online', common.mustCall(() => {
+      if (--waitOnline === 0)
+        for (const worker of workers)
+          if (worker.isConnected())
+            worker.send(i % 2 ? 'disconnect' : 'destroy');
+    }));
+
+    // These errors can occur due to the nature of the test, we might be trying
+    // to send messages when the worker is disconnecting.
+    worker.on('error', (err) => {
+      assert.strictEqual(err.syscall, 'write');
+      assert.strictEqual(err.code, 'EPIPE');
+    });
+
+    worker.once('disconnect', common.mustCall(() => {
+      for (const worker of workers)
+        if (worker.isConnected())
+          worker.send('disconnect');
+    }));
+
+    worker.once('exit', common.mustCall((code, signal) => {
+      assert.strictEqual(code, 0);
+      assert.strictEqual(signal, null);
+    }));
+  }
+} else {
+  process.on('message', (msg) => {
+    if (cluster.worker.isConnected())
+      cluster.worker[msg]();
+  });
+}