So I am a bit confused as I go about researching Full Page Caching for Community Edition 1.8. I have already implemented a Two Level Redis Cache, CDN, tuned MySQL's my.cnf for max performance (w/ the DB being on a separate server of course), and I have 2 servers hosting our store behind a load balancer. I say that to point out that I am not immediately jumping for the FPC before doing the initial performance tweaks.
I've never used Varnish before on any kind of site, let alone Magento, and I have never set up an FPC in Magento either. I understand Varnish to be a proxy that acts as a cross between a CDN and a page cache on it's own, sending data to the browser before the request even gets to the web server. And to my understanding, an FPC Module creates a cache locally that the webserver itself dishes out. I know that for both setups, you need to do some "Hole Punching" to get the dynamic content through to the browser (though the techniques are different, between using a module or using Varnish). Please correct me if I am misunderstanding anything here.
Up until just now, I thought of them as two separate entities that you could implement it help out your site, but now somethings I have read seem to imply the opposite. My original plan was to buy the "Warp Advanced Full Page Cache" module for Magento (Formerly the "Tiny Brick Lightspeed FPC", I believe) as it seems to be the most popular, if a touch on the pricier side (but, frankly, $350 isn't much for our company, especially for what it can do). Myself and 2 of my fellow developers were planning on learning out to implement it properly and fully within our own custom, homemade theme to maximize what we can get out of it. After that was done, at some point down the road, I figured I would look into implementing Varnish as well – but, as I said earlier, I had understood them to be separate.
Now, however, I am starting to come across extensions like this PageCache Powered by Varnish that is free, or this Vortex Cache Powered by Varnish Cache which is nearly $800 USD, that are Magento Full Page Cache modules that work directly with Varnish.
My question to you, stack exchange, is how should I be seeing a FPC and Varnish? As separate entities? If so, are they mutually exclusive? Are they two sides of the same coin that I should implement together? Or are they similar but neither exclusive nor inclusive of one another?
Can I use the Warp Advanced FPC I mentioned above with Varnish? Should I use it with Varnish? Or would it be better to use a different FPC if I plan on using Varnish? OR even further, is there an FPC so good that I don't need Varnish? Or vice-versa, should I just use Varnish and ditch the FPC idea?
Sorry for the wall of text, but I have been looking at a lot of articles, blogs, and forum posts, and I haven't been able to discern a definitive answer to those questions. I truly appreciate your help and input in this matter =)
Oh and lastly, a quick question about Varnish and webservers. Currently I am using the normal Apache LAMP stack setup, but for a while now I've been seeing people rave about using Nginx with Magento. I've done some tests myself, stress and load tests, and it seems that it can definitely work a bit better in the right conditions. As such, I was considering switching at some point in the near future. Would this in anyway affect my desire and decision to use an FPC and/or Varnish?
Thank you!!!
EDIT: Oh! And one more quick question – Since I have two servers hosting my site behind a load balancer (which is also a setup that can be increased horizontally should the need arise), I make full use of Redis and Memcached hosted on a separate server from the Web and DB ones for my sessions and each level of Magento's (well, Zend's) Two Level Cache. I assume the FPC would store it's data in one of those to systems? Would I need to have a specific extension to store it there or do they all do it? And while I assume not, would this affect Varnish in anyway? Thanks again!!
Best Answer
There are two difficult things in computer science:
Hole punching falls into category #2 :)
General
The best approach is to start at the lower points of the stack and optimize up to the frontend of Magento.
Database and Filesystem
Should always be the first areas to focus on. Because. I/O.
MyTop is a handy Linux based perl script that will mimic the Linux 'top' command and give you insight on the state of your MySQL instance(s).
Htop is a more robust top, The strace feature can help determine ins/outs of a process to find potential bottlenecks.
Iotop is another tool to consider for monitoring I/O.
Other handy utility scripts like mysqltuner.pl and mysql tunning primer can offer insight into your MySQL runtime variables and offer advice to help. Keep in mind these are meant to be guides as the best approach is always an evaluation of requirements and tuning based on known data gathered. Blindly doing so can cause more damage at times than good. And prematurely running these without at least 24 hours of mysql runtime variables may offer bad advice.
Keep in mind Percona, MariaDB and standard MySQL should work with all of the above. Favoring Percona as a MySQL fork, since Magento is so heavy on InnoDB and XtraDB offers many tools and enhancements to the db engine.
Apache or Nginx
Still using Apache as it has served many others well, myself included. I have used and configured Nginx as well. While it does offer some advantages there is a learning curve. While the two are both popular options, it does offer some advantages over Apache, one would be a smaller memory footprint. However a slim downed Apache running PHP-FPM will have a similar memory footprint.
Case in point:
To help facilitate this check out:
Utilizing a CDN to help take the ease off of either will help obviously but will have added benefit on frontend optimization since most end users browsers will be able to connect to both servers with the same number of connection limits. This also frees up Apache from not having to jump through checks and such just to serve up a simple static image. Lighthttpd is an option if you want to run a static web server just for content besides a CDN.
PHP
PHP-FPM and APC. Use them, strip out any unneeded or unrequired PHP modules not needed for Magento.
Magento codebase
AOE_TemplateHints is great to determine if your blocks are caching properly:
AOE_Profiler is good for profiling, be sure and enable its DB layer profiling (in a local/dev environment obviously). This in conjunction with the mytop tool mentioned previously makes finding bad behaving SQL an easier task.
3rd Party modules & Custom code
Some very good best practices for optimization from Magento themselves is a good read, and to keep in mind when reviewing 3rd party modules before using them. (there are lots of bad behaving ones IMO).
A tool Magniffer from Magento ECG will help easily identify bad behaving code based on the PDF provided above. It is symfony/php-parser based however but installable via composer.
Varnish
As an advocate of Varnish being the author was a FreeBSD kernel dev, it offers some crazy sub second load times. However if you even have some of the slightest differences in your templates that isn't out of box, you will spend time configuring varnish / magento to holepunch the content you need. Most I've seen will simply AJAX'ify the needed items uncached from Varnish.
There are a number of Magento modules to help facilitate this hole punching and caching:
Ultimately this should be at the last end of your optimization journey, and MAY require some customization to get things right.
Magento CE FPC
So far the best CE FPC I have found is: Lesti::FPC
it is a very well put together (all observer based) open-source and free FPC for Community.
At the end of the day use your own testing and judgement.
Some further reading: