应用程序加速Ruby on Rails

Question

I have a controller action which is taking 10 seconds to run. Most of the time is being spent in a view which is a large file.(more than 1500 lines). How shall I go about debugging the speed issue?

Answer 1

Yuo can try NewRelic for example. I used the free version a few years ago and you can see the overall performance and especially the slow calls pretty good.
As far as I remember you only have to install a gem, configure some things and it's good to go.

Answer 2

Ruby and Rails have basic profiling tools that can help you. Take a look at this Rails guide: Performance Testing Rails Applications .

That page describes how you can write test cases meant for benchmarking, to prevent performance regressions and how you can do profiling, which could be as simple as:

rails profiler 'Ruby.code.to.run'

If that doesn't do it for you, then consider using New Relic . But I would also take a look at Rack-Bug (btw, it has a Rails 3 branch for Rails 3). Rack-Bug is a debugging toolbar that gives you lots of awesome metrics about where time has been spent in a request and it does so straight in the browser, alongside the normal response, so it's the least painful.

Now, what you're doing is wrong:

• you should avoid fat views, as fat views are hard to test, hard to debug and hard to profile
• you should avoid slow code in your web process, because it will block other clients from accessing your web server, instead move all that logic out into an asynchronous job queue

So consider moving this processing into a jobs queue. Delayed_job is pretty reliable, properly maintained and works with Rails 3.

So your view will register a new job and return. And when the job is done you'll set a flag somewhere that it is done. Then with a special API call you can check for its completeness from client-side Javascript once every few seconds. And once completed you can show the results, redirect or start the download or whatever, again from Javascript.

And if the above is not an option (maybe this is a page that shows a report that should be instant), the first bottleneck you should consider are the SQL queries getting executed, so get familiar with MySQL's DESCRIBE command (or PostgreSQL's EXPLAIN ). It's easy that way to see where you need indexes.

Answer 3

NewRelic is the best way to analyze the application .

With the below point , you can modify your code for speed-up of your application .

• The N+1 query problem
• Testing N+1
• Nested eager loading
• Indirect eager loading
• Rails grouping and aggregate calculations

Answer 4

I would suggest to wrap some small pieces of your view into benchmark blocks and see in the log/development.log where are the slow parts.

<% benchmark "Showing users" do %>
  <!-- ... -->
<% end %>

<% benchmark "Performing some calculations" do %>
  <!-- ... -->
<% end %>

The best case will be that you find a few places where 90% time is spent. Then you can work on them to significantly improve the performance.