Railscasts - Request Profiling

#98

Mar 24, 2008

Request Profiling

You can use profiling to determine where the performance bottlenecks are in specific Rails actions. Watch this episode for details.

Tags: tools performance

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alternative download for iPod & Apple TV (20.1 MB, 10:53)

Resources

# config/environments/staging.rb
config.cache_classes = true
config.action_controller.consider_all_requests_local = false
config.action_controller.perform_caching             = true
config.action_view.cache_template_loading            = true

config.log_level = :debug

# lib/products_index_profiler.rb
get '/products'
say "GET #{path}"

$ script/server -e staging
$ sudo gem install ruby-prof
$ RAILS_ENV=staging script/performance/request lib/products_index_profiler.rb

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19 comments

1. Carl Mar 24, 2008 at 12:36

Good screencast. I'd like to see more information on how you can optimize things once you narrow down the culprits. Maybe a checklist of 'gotchas' or something like that. Especially any that are common and not well known.

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2. eddiemoses81@yahoo.com Mar 24, 2008 at 22:52

Great screencast! Thank you very much for all this great information.

Thanks
Eddie Moses

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3. myspace proxy Mar 25, 2008 at 08:38

Cool screencasts.. Thanks for sharing.

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4. Sam Mar 27, 2008 at 16:10

Little typo detected

should be:
sudo gem install ruby-prof

Great podcast, thanks for the info

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5. AJ Mar 27, 2008 at 20:42

@Sam:
its ruby-perf only. (perf => performance)

Nice screencast. I really need to measure performance issues of my app and tutorials like this are of great help. :)

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6. Ryan Bates Mar 29, 2008 at 10:34

@Carl, I did some previous episodes on optimization, but they don't cover everything so you can expect some more in the future. You can find them out here.
http://railscasts.com/tags/1

@Sam, thanks. Fixed.

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7. Taylor Redden Mar 29, 2008 at 11:47

Hey Ryan, Passenger (mod_rails) is looking for someone to redo there screencast before they release. I think you would be the perfect person for it.

check it out here...
http://izumi.plan99.net/blog/

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8. Ryan Bates Mar 29, 2008 at 16:51

@Taylor, thanks for the link. I'll look into doing it. :)

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9. JWBnyc Apr 11, 2008 at 16:48

I'm able to run a script, but the files don't contain useful numbers. On Ubuntu (32bit), the first column of profile-flat contains a mix of inf and nan. I'll dig into this, but if you have some guidance, it would be greatly appreciated.

I've tried it on 32-bit Vista, 64-bit Ubuntu & 32-bit Ubuntu. They all report some sort of error. On 64-bit Ubuntu, it aborts with an Integer range error. On Vista, it complains that the files (txt & html) don't exist (though I can open them and see listings for all the methods with no timings). On 32bit Ubuntu, it complains twice about "Could not get a file descriptor referring to the console." These last two create files though the content lacks timings.

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10. kino May 23, 2008 at 01:53

In the case of the discipline of pure reason, our a posteriori knowledge, then, teaches us nothing whatsoever regarding the content of the objects in space and time, as is evident upon close examination.

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11. Phil Jul 18, 2008 at 05:04

How do you get ruby-prof installed under osx? I've tried under both Tiger and Leopard and I get
No definition for prof_get_cpu_frequency

No definition for prof_set_cpu_frequency

on both

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12. Moe Aug 08, 2008 at 03:16

I get the same message No definition for prof_get_cpu_frequency both under OS X (Leopard) & Linux (CentOS 5).

When I run the request script I get following:
Warming up once
0.03 sec, 1 requests, 29 req/sec

Profiling 100x
`gem install ruby-prof` to use the profiler

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13. grosser Aug 19, 2008 at 00:12

same here... maybe a gems 1.2 issue

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14. grosser Aug 22, 2008 at 22:25

Only thing i found is this:

Please use Jeremy Kamper's ruby-prof :http://github.com/jeremy/ruby-prof/tree/master

gem sources -a http://gems.github.com
sudo gem install jeremy-ruby-prof

but does not work for me either...

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15. Sean Schofield Aug 28, 2008 at 16:52

I had the same problem as everyone above and also failed to get it working with jeremy's gem. I did however get it to work after some investigation.

I took a look at the rails source and it requires ruby-prof 0.6.1. After installing Jeremy's gem I realized it had a slightly different name (jeremy-ruby-prof vs. ruby-prof.) That's probably a github thing but it wasn't satisfying the gem command inside of rails.

So I built the gem from ruby forge source (rake gem, and install manually from the pkg location) and it worked!

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16. Lewis Hoffman Sep 03, 2008 at 13:44

Thanks Sean!! that fixed it for me too.

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17. Darius Sep 29, 2008 at 14:17

For integration testing you can define session[:user] by adding a second hash, for the session.