From 22f51a6a8319b312ed5899a979d9e57b5cefde0e Mon Sep 17 00:00:00 2001
From: cjihrig <cjihrig@gmail.com>
Date: Thu, 27 Sep 2018 09:35:21 -0400
Subject: [PATCH] cluster: use Map to track callbacks
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Use a Map to avoid delete operations in callback tracking.

PR-URL: https://github.com/nodejs/node/pull/23125
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
---
 lib/internal/cluster/utils.js | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/lib/internal/cluster/utils.js b/lib/internal/cluster/utils.js
index ba72ff90945d3c..94b82d039a098a 100644
--- a/lib/internal/cluster/utils.js
+++ b/lib/internal/cluster/utils.js
@@ -7,7 +7,7 @@ module.exports = {
   handles: {} // Used in tests.
 };
 
-const callbacks = {};
+const callbacks = new Map();
 var seq = 0;
 
 function sendHelper(proc, message, handle, cb) {
@@ -18,7 +18,7 @@ function sendHelper(proc, message, handle, cb) {
   message = util._extend({ cmd: 'NODE_CLUSTER' }, message);
 
   if (typeof cb === 'function')
-    callbacks[seq] = cb;
+    callbacks.set(seq, cb);
 
   message.seq = seq;
   seq += 1;
@@ -34,9 +34,13 @@ function internal(worker, cb) {
 
     var fn = cb;
 
-    if (message.ack !== undefined && callbacks[message.ack] !== undefined) {
-      fn = callbacks[message.ack];
-      delete callbacks[message.ack];
+    if (message.ack !== undefined) {
+      const callback = callbacks.get(message.ack);
+
+      if (callback !== undefined) {
+        fn = callback;
+        callbacks.delete(message.ack);
+      }
     }
 
     fn.apply(worker, arguments);