http: start connections checking interval on listen

Fixes: nodejs#48604.

lib/_http_server.js

@@ -497,14 +497,14 @@ function storeHTTPOptions(options) {
   }
 }
 
-function setupConnectionsTracking(server) {
+function setupConnectionsTracking() {
   // Start connection handling
-  server[kConnections] = new ConnectionsList();
+  this[kConnections] = new ConnectionsList();
 
   // This checker is started without checking whether any headersTimeout or requestTimeout is non zero
   // otherwise it would not be started if such timeouts are modified after createServer.
-  server[kConnectionsCheckingInterval] =
-    setInterval(checkConnections.bind(server), server.connectionsCheckingInterval).unref();
+  this[kConnectionsCheckingInterval] =
+    setInterval(checkConnections.bind(this), this.connectionsCheckingInterval).unref();
 }
 
 function httpServerPreClose(server) {
@@ -542,11 +542,12 @@ function Server(options, requestListener) {
   this.httpAllowHalfOpen = false;
 
   this.on('connection', connectionListener);
+  this.on('listening', setupConnectionsTracking);
 
   this.timeout = 0;
   this.maxHeadersCount = null;
   this.maxRequestsPerSocket = 0;
-  setupConnectionsTracking(this);
+
   this[kUniqueHeaders] = parseUniqueHeadersOption(options.uniqueHeaders);
 }
 ObjectSetPrototypeOf(Server.prototype, net.Server.prototype);
@@ -558,6 +559,10 @@ Server.prototype.close = function() {
 };
 
 Server.prototype.closeAllConnections = function() {
+  if (!this[kConnections]) {
+    return;
+  }
+
   const connections = this[kConnections].all();
 
   for (let i = 0, l = connections.length; i < l; i++) {
@@ -566,6 +571,10 @@ Server.prototype.closeAllConnections = function() {
 };
 
 Server.prototype.closeIdleConnections = function() {
+  if (!this[kConnections]) {
+    return;
+  }
+
   const connections = this[kConnections].idle();
 
   for (let i = 0, l = connections.length; i < l; i++) {

lib/https.js

@@ -94,8 +94,9 @@ function Server(opts, requestListener) {
 
   this.timeout = 0;
   this.maxHeadersCount = null;
-  setupConnectionsTracking(this);
+  this.on('listening', setupConnectionsTracking);
 }
+
 ObjectSetPrototypeOf(Server.prototype, tls.Server.prototype);
 ObjectSetPrototypeOf(Server, tls.Server);
 

test/parallel/test-http-server-connections-checking-leak.js

@@ -0,0 +1,45 @@
+'use strict';
+
+// Flags: --expose-gc
+
+const common = require('../common');
+if (!common.hasCrypto) { common.skip('missing crypto'); }
+const onGC = require('../common/ongc');
+const http = require('http');
+const https = require('https');
+
+// Check that creating a server without listening is not leaking resources.
+const max = 100;
+
+// HTTP
+{
+  const gcListener = common.mustCall(max);
+
+  for (let i = 0; i <= max; i++) {
+    if (i % 100 === 0) {
+      global.gc();
+    }
+
+    const server = http.createServer((req, res) => {});
+    onGC(server, { ongc: gcListener });
+  }
+
+  global.gc();
+}
+
+// HTTPS
+
+{
+  const gcListener = common.mustCall(max);
+
+  for (let i = 0; i <= max; i++) {
+    if (i % 100 === 0) {
+      global.gc();
+    }
+
+    const server = https.createServer((req, res) => {});
+    onGC(server, { ongc: gcListener });
+  }
+
+  global.gc();
+}