Performance issue for Rails: How to send gzip asse

Question

I am using rails asset pipeline feature in production environment.I have written some setting in nginx to send files in the gzip format and files are coming properly in gzip format.I guess the browser is automatically decoding it so hence i am not able to find out whether the js files are comming in gizp format or not.

I have put the following command and i am getting "content-encoding: zip" in the response.

curl -v -H 'Accept-Encoding: gzip' -o /dev/null http://www.example.com/assets/style.css 2>&1 | grep -i Content-Encoding

I have written below setting in nginx to send files in the gzip format and files are coming properly in gzip format.

location ~ ^/(assets)/  {
        root /home/webuser/app/woa/public;
        gzip_static on;
        expires max;
        add_header Cache-Control public;
        # access_log /dev/null;
        }

How will i come to know that files are coming in gzip format or not??

Also please suggest any other options which can be helpful to improve the performance of the site.

Answer 1

Not a direct answer to your first question(if you solved it please do explain), but for improving site performance remember the Perfomance Golden Rule:

80-90% of the end-user response time is spent on the front-end. Start there.

Below is a non-exhaustive list areas of improvement for increasing performance in a Rails app:

Diagnosing the Problem:

YSlow / Google Page Speed

A useful diagonsis tool for identifying perfomance issues is Yslow or Google Page Speed They are browser extensions that diagnoses and identifies common issues slowing down your app (particularly on the front end).

Back-end Tools

For your Rails back-end I recommend incorporating tools such as Bullet & NewRelic directly into your development processes, so that while you're developing you can spot bad queries immediately while they are still easy to fix.

Check Server Console Logs

Checking your server logs is an effective method for diagnosing what components of your Rails app is taking the longest. E.g. below are sample logs from two unrelated production Rails apps running in my local development environment:

# app1: slowish
  Rendered shared/_header.html.erb (125.9ms)
  Rendered clients/details.html.erb within layouts/application (804.6ms)
  Completed 200 OK in 3655ms (Views: 566.9ms | ActiveRecord: 1236.9ms)

# app2: debilitatingly slow
  Rendered search/_livesearch_division_content.js.erb (5390.0ms)
  Rendered search/livesearch.js.haml (34156.6ms)
  Completed 200 OK in 34173ms (Views: 31229.5ms | ActiveRecord: 2933.4ms)

App1 & App2 both suffer from performance issues, but App2's performance issues are clearly debilitatingly slow. (34 seconds!) But with these server logs, I know for App1 that I should look into clients/details.html.erb, and that for App2 I absolutely need to investigate search/livesearch.js.haml.

Improving Front-end Performance

Budget your page size strictly

To maintain fast load times you need reduce the amount/size of your page assets (JS/CSS/Images). So think about your page size like a budget. For example, Hootesuite recently declared that their home page now has a strict page-size budget of 1 mb. No exceptions. Now check out their page. Pretty fast isn't it?

Easy wins for reducing your page size include stripping out unused JS or CSS files, including them only where needed, and changing static images into much smaller vectors.

Serve smaller image resolutions based on screen width

Image loading is a large cause of slow page loading times. A large 5mb image used in the background of your splash page can easily be brought down to 200kb-400kb in size, and still be high quality enough to be hardly indistinguishable from the higher resolution original. The difference in page load times will be dramatic.

You should do these same improvements to user uploaded images as well. E.g. if your website's user avatars are 50px by 50px in size, but a user uploads a 5mb image for his avatar, then it's essential that you serve the image with lower file sizes and resolutions to fit exactly how it will be shown on your site.

Carrierwave, Fog, and rmagick are popular gems used with Amazon S3 to achieve better image loading. With that collection of packages you can dynamically serve smaller image resolutions based upon the screen size of each user. You can then use media queries so that mobile device get served smaller resolution sizes of images compared to your users with Retina screens.

Use a Content Delivery Network to speed up asset loading

Adding on to the last point, you can speed up asset/image loading times by using a Content Delivery Network (CDN's) such as Cloudfront. CDN's distribute assets across many servers, then serve assets to your users via servers that are located the closest to the user making the request.

Fingerprint Static Assets

When static assets are fingerprinted, when a user visits your page their browser will cache a copy of these assets, meaning that they no longer need to be reloaded again for the next request.

Move Javascript files to the bottom of the page

Javascript files placed at the bottom of the page will load after the page loads. If javascript assets are placed on the top of the page, then the page will remain blank as a user's browser attempts to load your javascript files. Fortunately Rails will automatically place javascript files to the bottom of your page if you use the asset pipeline or specify javascript files using the javascript_include_tag.

EDIT: Most modern browsers now optimize Javascript loading automatically so you can mostly ignore this advice.

Improving Back-end Performance

Cache, Cache, Cache!

Among all backend performance optimizations, caching is among the most effective for producing dramatic performance gains. A well implemented caching regime can greatly minimize the damage of inefficient queries within your backend during periods of high scalability. Content that is accessed frequently, yet changes relatively infrequently, benefits the most from caching.

Caching is so powerful that it brought down the page load times of App2 mentioned above from 34 seconds to less than a second in production. There is simply no other performance enhancement on the back-end that can come even close to what we got from caching.

Overall, when doing performance optimization with caching, start high then go low. The gains you will get will be greater for less effort.

From high to low, some types of caching available to you are:

• HTTP caching (does not cache your server, but involves a user's browser caching content locally by reading HTTP headers)
• Page caching (memcache)
• Action Caching (memcache)
• Fragment caching (memcache) or Russian doll caching (a favoured technique for caching with fragments)
• Model caching (memcache)

To learn more about caching, a good place to start is here: http://guides.rubyonrails.org/caching_with_rails.html

Index Everything

If you are using SQL for your database layer, make sure that you specify indexes on join tables for faster lookups on large associations used frequently. You must add them during migrations explicitly since indexing is not included by default in Rails.

N+1 queries

A major performance killer for Rails apps using relational (SQL) databases are N+1 queries. If you see in your logs that your app is making many database read/writes for a single request, then it's often a sign you have N+1 queries. N+1 queries are easy to miss during development but can rapidly cripple your app as your database grows (I once dealt with an that had twelve N+1 queries. After accumulating only ~1000 rows of production data, some pages began taking over a minute to load).

Bullet is a great gem for catching N+1 queries early as you develop your app. A simple method for resolving N+1 queries in your Rails app is to eager load the associated Model where necessary. E.g. Post.all changes to Post.includes(:comments).all if you are loading all the comments of each post on the page.

Upgrade to Rails 4 and/or Ruby 2.1.x or higher

The newer version of Rails contains numerous performance improvements that can speed up your app (such as Turbolinks.)

Ruby 2.1.x+ contain much better garbage collection over older versions of Ruby. So far reports of people upgrading have found notable performance increases from upgrading.

---

I am missing many improvements here, but these are a few performance improvements that I can recommend. I will add more when I have time.