Use an object instead of an array to store connection callbacks. This way we can ensure a callback is never called after its stop handle is called.

packages/livedata/livedata_server.js

@@ -995,9 +995,12 @@ _.extend(Subscription.prototype, {
 Server = function () {
   var self = this;
 
-  // List of callbacks to call when a new connection comes in to the
-  // server and completes DDP version negotiation.
-  self.connectionCallbacks = [];
+  // Map of callbacks to call when a new connection comes in to the
+  // server and completes DDP version negotiation. Use an object instead
+  // of an array so we can safely remove one from the list while
+  // iterating over it.
+  self.connectionCallbacks = {};
+  self.nextConnectionCallbackId = 0;
 
   self.publish_handlers = {};
   self.universal_publish_handlers = [];
@@ -1073,11 +1076,12 @@ _.extend(Server.prototype, {
 
     fn = Meteor.bindEnvironment(fn, "onConnection callback");
 
-    self.connectionCallbacks.push(fn);
+    var id = self.nextConnectionCallbackId++;
+    self.connectionCallbacks[id] = fn;
 
     return {
       stop: function () {
-        self.connectionCallbacks = _.without(self.connectionCallbacks, fn);
+        delete self.connectionCallbacks[id];
       }
     };
   },
@@ -1092,9 +1096,11 @@ _.extend(Server.prototype, {
       // Creating a new session
       socket._meteorSession = new Session(self, version, socket);
       self.sessions[socket._meteorSession.id] = socket._meteorSession;
-      _.each(self.connectionCallbacks, function (callback) {
-        if (socket._meteorSession)
+      _.each(_.keys(self.connectionCallbacks), function (id) {
+        if (_.has(self.connectionCallbacks, id) && socket._meteorSession) {
+          var callback = self.connectionCallbacks[id];
           callback(socket._meteorSession.connectionHandle);
+        }
       });
     } else if (!msg.version) {
       // connect message without a version. This means an old (pre-pre1)

packages/livedata/livedata_server_tests.js

@@ -52,6 +52,38 @@ Tinytest.addAsync(
 );
 
 
+testAsyncMulti(
+  "livedata server - onConnection doesn't get callback after stop.",
+  [function (test, expect) {
+    var afterStop = false;
+    var expectStop1 = expect();
+    var stopHandle1 = Meteor.onConnection(function (conn) {
+      stopHandle2.stop();
+      stopHandle1.stop();
+      afterStop = true;
+      // yield to the event loop for a moment to see that no other calls
+      // to listener2 are called.
+      Meteor.setTimeout(expectStop1, 10);
+    });
+    var stopHandle2 = Meteor.onConnection(function (conn) {
+      test.isFalse(afterStop);
+    });
+
+    // trigger a connection
+    var expectConnection = expect();
+    makeTestConnection(
+      test,
+      function (clientConn, serverConn) {
+        // Close the connection from the client.
+        clientConn.disconnect();
+        expectConnection();
+      },
+      expectConnection
+    );
+  }]
+);
+
+
 Meteor.methods({
   livedata_server_test_inner: function () {
     return this.connection.id;