Authenticated user loggouts after server restart

I have a node application and whenever I edit/update a .js file, users are logging out. I'm using passport-local with express.io.

Also I'm using mongoose and socket.io.

app.configure(function() {
    app.use(express.logger('dev'));
    app.use(express.cookieParser());
    app.use(bodyParser.json());
    app.use(bodyParser.urlencoded({ extended: true }));
    app.set('view engine', 'ejs');
    app.use(express.session({
        key: 'session',
        secret: '111'
    }));
    app.use(passport.initialize());
    app.use(passport.session());
    app.use(flash());

});

How to make users log in forever?

Solved : NodeJS + Express + Mongo Session storage