Rails 4 assets:precompile very slow all time

rubyonrails-talk
1

Hi, If I good understand, Rails 4 compile only changed assets ? Like gem turbo-sprockets-rails3 ? In this case, I don’t understand why launch 2 times ‘rake assets:precompile’, take same time (~10min). Result a very slow deploy…

2

Any idea ? Just tell me if I understand the process

3

same trouble, any ideas?

4

Yes, in theory, that’s the way it works. There are a number of things that could be going on.

Your long compile time could be a number of issues. I would start with the easiest which is corrupted caches. Run the following:

rake assets:clean assets:clobber

This wipes everything out. Now run rake assets:precompile. This will be a long one since everything is being compiled. After that, you should be able to make a change and only the changed asset will be recompiled.

If you’re still having long run times, you may need to clean things up. There are several suggestions I could make:

  1. I only include images in the asset pipeline that get used on every page or the majority of pages such as a logo, background for a header, etc. Images that only get used on one page I keep in public/images and refer to them statically. The reason for this is that every image in the app/assets/images directory gets fingerprinted and copied to /public/assets. The only advantage to this is that the images are pre-loaded in the browser. However, it pre-loads them on every page, regardless of whether that page uses the images or not. To me, this is a lot of overhead and for images that I use only on one page or in one area I don’t run through the pipeline.

  2. Watch your filenames. Don’t name a stylesheet mystylesheet.css.scss if, in fact, the file only contains only CSS and no SASS code in it. It will unnecessarily get pre-processed when no pre-processing is required. Same goes for erb & coffee.

  3. This is a personal belief, a lot of developers would disagree, but I don’t ever use require_tree or require_directory in the manifest. First, with stylesheets, order is important so I need to require stylesheets in the right order and second, I want to be sure that only stylesheets and javascript I specifically require are included.

  4. You may have issues with your deployment tool. Capistrano, at one point, was touching every asset causing the pipeline to completely recompile regardless of whether changes had been made or not. I believe this was fixed, but I’m not positive.

Beyond this, I’m open for other’s comments. Hopefully, some of these suggestions will help improve your times.

5

Hi, If I good understand, Rails 4 compile only changed assets ? Like gem turbo-sprockets-rails3 ? In this case, I don't understand why launch 2 times 'rake assets:precompile', take same time (~10min). Result a very slow deploy...

Yes, in theory, that's the way it works. There are a number of things that could be going on.

Your long compile time could be a number of issues. I would start with the easiest which is corrupted caches. Run the following:

rake assets:clean assets:clobber

This wipes everything out. Now run rake assets:precompile. This will be a long one since everything is being compiled. After that, you should be able to make a change and only the changed asset will be recompiled.

If you're still having long run times, you may need to clean things up. There are several suggestions I could make:

1) I only include images in the asset pipeline that get used on every page or the majority of pages such as a logo, background for a header, etc. Images that only get used on one page I keep in public/images and refer to them statically. The reason for this is that every image in the app/assets/images directory gets fingerprinted and copied to /public/assets. The only advantage to this is that the images are pre-loaded in the browser. However, it pre-loads them on every page, regardless of whether that page uses the images or not. To me, this is a lot of overhead and for images that I use only on one page or in one area I don't run through the pipeline.

2) Watch your filenames. Don't name a stylesheet mystylesheet.css.scss if, in fact, the file only contains only CSS and no SASS code in it. It will unnecessarily get pre-processed when no pre-processing is required. Same goes for erb & coffee.

3) This is a personal belief, a lot of developers would disagree, but I don't ever use require_tree or require_directory in the manifest. First, with stylesheets, order is important so I need to require stylesheets in the right order and second, I want to be sure that only stylesheets and javascript I specifically require are included.

4) You may have issues with your deployment tool. Capistrano, at one point, was touching every asset causing the pipeline to completely recompile regardless of whether changes had been made or not. I believe this was fixed, but I'm not positive.

Beyond this, I'm open for other's comments. Hopefully, some of these suggestions will help improve your times.

I went through a phase on one server where my compile times would go up and up until I restarted the server, then they would be blinding fast again for a while, then get steadily worse. I don't remember changing anything, but the behavior went away. Might have been an update to nodejs from regular apt-get updates that did that. Which JavaScript engine are you running on your server?

Walter