Speedup Symfony2 on Vagrant boxes

• Update: Added requirements to configure Vagrant and Virtualbox before trying my change.
• Update 2: Added link to Virtualbox Guest Additions plugin for Vagrant, thanks Peter Kruithof for the hint.

Using Symfony2 inside a Vagrant box is considered to be very slow (here, here), even when using NFS. I can confirm the experience and know many others that reported the same.

Before doing this changes make sure:

• You are using Vagrant 1.2 (not sure that makes a difference though)
• You are using NFS with Vagrant (More). If you are on Windows then this can already be the problem (Virtualbox FS is slow with Symfony, because of the large number of files.)
• You have the Vbox Guest Additions on the guest that match your system (Vagrant Plugin, Manual Update)
• You have an opcode cache installed, either `apc` or `opcache`.
• You disable `xdebug` or `xhprof`.

Without looking at an actual benchmark (mistake!) I always considered the problem to be related to the huge number of files that a Symfony project normally ships with and the I/O that is generated from filemtime calls to check if the configuration files have changed.

This is just a small part, there are other bottlenecks that I have found after finally doing some benchmarking with XHProf, leading to a simple fix:

1. Monolog logs to the NFS share and the huge number fwrite take their toll.
2. Writing compiled Twig templates to the NFS share using file_put_contents.
3. Assetic: Scanning for stylesheets and javascripts within templates is very slow, causing lots of I/O on the NFS share and CPU and changing it to using explicit bundling in the app/config/config.yml helps alot. You can use a cronjob deployed by Puppet/Chef that invokes the `assetic:dump` command with a `--watch` flag in the background.
4. JMSDiExtraBundle scans for Services to check for changes on service objects.
5. ReplaceAliasWithActualDefinitionPass in Symfony DIC uses a set of recursive algorithms to replace aliases with the real services. That takes a huge amount of time in bigger applications including amounting calls to methods inside the pass over 100.000 times.

The slowest bottlenecks listed (1-4) are I/O bound, directly related to NFS. To fix this just change the cache AND the log directory to sys_get_temp_dir() or shared memory (/dev/shm) instead of writing to the NFS share. I actually tried this before, but since I forgot the log directory, this felt equally slow and I reverted the change.

Here is the code you should add to your AppKernel to give you a considerable performance boost on a Vagrant box:

<?php

class AppKernel extends Kernel
{
    // ...

    public function getCacheDir()
    {
        if (in_array($this->environment, array('dev', 'test'))) {
            return '/dev/shm/appname/cache/' .  $this->environment;
        }

        return parent::getCacheDir();
    }

    public function getLogDir()
    {
        if (in_array($this->environment, array('dev', 'test'))) {
            return '/dev/shm/appname/logs';
        }

        return parent::getLogDir();
    }
}

This brings the page rendering speeds down to between 0.5 and 1.5 seconds, which is quite normal for the development environment even outside a virtual machine.

This tip obviously works for any kind of application that has a I/O intensive development environment: Don't perform this operations on the NFS share unless you wan't to suffer.