assets:precompile still incredibly slow

[chrisnicola]

I'm seeting times of several minutes to compile with compass. Same issue as the one linked below I assume. Is there any further progress or guidance on this problem yet? Was it fixed or is it still a known issue?

Compass/compass#516

[chriseppstein]

I decided to go ahead with the release knowing there were still some performance issues -- but the rest of the project was stable and the API was solid.

Several minutes is clearly unacceptable and we need to get to the bottom of it.

[chrisnicola]

Thanks, let me know if I can help, I'd be happy to run some tests for you.

[chriseppstein]

Help would be greatly appreciated. I have found that most of the issues are related to performance of @import when sass-rails delegates finding imports to sprockets. But I really need hard data to go on from profiling.

[jdelStrother]

I spent quite a long time going through profile dumps of our assets compilation (which currently takes nearly 3 minutes on our production servers), and basically came to the conclusion there were no easy performance gains to be found in compass, sprockets, or trail. Concatenating all the compass files I needed into a single file helped a bit, but it only saved 5-10%.

I'm working on an alternative approach - don't blow away the cache that sprockets worked so hard to create before every 'rake assets:precompile'. I'm still figuring out its problems and the correct way of implementing it at rails/rails#5497

[siefca]

In my case (compiling screen.css and print.css separately) and using scaffolded examples:

real    6m29.579s
user    6m7.224s
sys     0m18.959s

[chrisnicola]

Might be worth noting I've only really experienced this problem heavily with twitter bootstrap conversions from less to scss. I've tried a couple, notable compass_twitter_bootstrap and bootstrap-sass and both have compile time problems, taking about 4 minutes on my machine (the former is a little slower).

Using bootstrap-rails (which uses less with the asset pipeline) cuts this down to about 30s.

Not sure if that's helpful.

[chrisnicola]

The fix to sass/sass#337 actually fixes this completely for me. Just found it.

You'll need to use the master branch in your Gemfile.

  gem 'sass', git: 'git://github.com/nex3/sass.git'

[macmartine]

@LucisFerre I'm using sass-rails, and not using the sass gem. It's still ridiculously slow. I tried also installing the master sass branch as suggested, but I'm assuming the problem it still in the sass-rails gem? Any idea how I can get around this? It's unbearable.

[chrisnicola]

No it's in the sass gem and you shouldn't need the master branch anymore it's been released, just gem 'sass' now.

How slow is slow? Mine takes about 30s.

[macmartine]

Ok, thanks. Maybe this issue isn't exactly the one I'm seeing. Each time I reload a page in development mode it takes yes, about 30 seconds. That can't be normal? I'm not sure if it's specifically compass related or sass but there's no way I can continue developing with page loads that take this long so I'm trying to figure out the culprit. Thanks!.

[jdelStrother]

If you have a number of separate css/js files, try setting config.assets.debug = false in your development.rb, which will join them into a single file (like in production). It's significantly faster for us that way.

[macmartine]

If I just use the sass gem, and not sass-rails, I hit this Compass/compass#654
With sass-rails and not this gem I'm still seeing 20+ second page loads. It's starting to look like I need to yank compass out of my app...

[chriseppstein]

@macmartine compass does a lot of importing and importing via sprockets in rails is very slow. You may see better performance if you can isolate your compass imports to a single partial at the start of the stylesheet. If this doesn't sound like what's going on here, can you please zip up your stylesheets and relevant configuration into a minimal rails app that reproduces your issue and I will investigate what is going on.

In the meantime, you may find that using bundle exec compass watch makes development much more responsive.

[chrisnicola]

Yeah though @chriseppstein I havn't had problems whether or not I use one or multiple output CSS files. That said I just have one, everything is output to application.css now which I agree is the best pattern for using compass and rails.

Macmartine, try not using Webrick, it is slow as crap. Octopress generates a static site and also uses Compass. I get 30s page loads with Webrick on my VM for every page load even though it doesn't actually recompile each load. Switching to Thin or something else fixes it instantly. Honestly don't understand why Webrick is a default.