cluster: wait on servers closing before disconnect

Before this, cluster behaves not the way it is documented.  When
disconnect is triggered, worker must wait for every server is closed
before doing disconnect actually.

Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
PR-URL: #1400
Fixes: #1305

lib/cluster.js

@@ -627,12 +627,26 @@ function workerInit() {
 
   Worker.prototype.disconnect = function() {
     this.suicide = true;
+    var waitingHandles = 0;
+
+    function checkRemainingHandles() {
+      waitingHandles--;
+      if (waitingHandles === 0) {
+        process.disconnect();
+      }
+    }
+
     for (var key in handles) {
       var handle = handles[key];
       delete handles[key];
-      handle.close();
+      waitingHandles++;
+      handle.owner.close(checkRemainingHandles);
     }
-    process.disconnect();
+
+    if (waitingHandles === 0) {
+      process.disconnect();
+    }
+
   };
 
   Worker.prototype.destroy = function() {

test/parallel/test-cluster-worker-wait-server-close.js

@@ -0,0 +1,42 @@
+'use strict';
+
+var common = require('../common');
+var assert = require('assert');
+var cluster = require('cluster');
+var net = require('net');
+
+if (cluster.isWorker) {
+  net.createServer(function(socket) {
+    // Wait for any data, then close connection
+    socket.on('data', socket.end.bind(socket));
+  }).listen(common.PORT, common.localhostIPv4);
+} else if (cluster.isMaster) {
+
+  var connectionDone;
+  var ok;
+
+  // start worker
+  var worker = cluster.fork();
+
+  // Disconnect worker when it is ready
+  worker.once('listening', function() {
+    net.createConnection(common.PORT, common.localhostIPv4, function() {
+      var socket = this;
+      worker.disconnect();
+      setTimeout(function() {
+        socket.write('.');
+        connectionDone = true;
+      }, 1000);
+    });
+  });
+
+  // Check worker events and properties
+  worker.once('disconnect', function() {
+    assert.ok(connectionDone, 'disconnect should occur after socket close');
+    ok = true;
+  });
+
+  process.once('exit', function() {
+    assert.ok(ok);
+  });
+}