lib: emit listening event once when call listen twice

Author: theanarkh

lib/net.js

@@ -1969,7 +1969,11 @@ function listenInCluster(server, address, port, addressType,
       const ex = new ExceptionWithHostPort(err, 'bind', address, port);
       return server.emit('error', ex);
     }
-
+    // If there was a handle, just close it to avoid fd leak
+    // but it doesn't look like that's going to happen right now
+    if (server._handle) {
+      server._handle.close();
+    }
     // Reuse primary's server handle
     server._handle = handle;
     // _listen2 sets up the listened handle, it is still named like this
@@ -1998,6 +2002,8 @@ Server.prototype.listen = function(...args) {
 
   options = options._handle || options.handle || options;
   const flags = getFlags(options.ipv6Only);
+  //  Refresh the id to make the previous call invalid
+  this._listeningId++;
   // (handle[, backlog][, cb]) where handle is an object with a handle
   if (options instanceof TCP) {
     this._handle = options;

test/parallel/test-net-listen-twice.js

@@ -0,0 +1,42 @@
+'use strict';
+const common = require('../common');
+const net = require('net');
+const cluster = require('cluster');
+const assert = require('assert');
+const tmpdir = require('../common/tmpdir');
+
+if (cluster.isPrimary) {
+  const worker = cluster.fork();
+  worker.on('exit', common.mustCall((code) => {
+    assert.ok(code === 0);
+  }));
+} else {
+  tmpdir.refresh();
+  const server = net.createServer();
+  server.listen();
+  try {
+    // Currently, we can call `listen` twice in cluster worker,
+    // if we can not call `listen` twice in the futrue,
+    // just skip this test.
+    server.listen(common.PIPE);
+  } catch (e) {
+    console.error(e);
+    process.exit(0);
+  }
+  let i = 0;
+  process.on('internalMessage', (msg) => {
+    if (msg.cmd === 'NODE_CLUSTER') {
+      if (++i === 2) {
+        setImmediate(() => {
+          // The last `listen` is valid
+          assert.ok(server.address() === common.PIPE);
+          server.close(() => {
+            process.disconnect();
+          });
+        });
+      }
+    }
+  });
+  // Must only call once
+  server.on('listening', common.mustCall());
+}