How can I troubleshoot extremely slow rake assets:precompile on heroku?

Question

rake assets:precompile is fast (<10 seconds) both locally and when I run it on heroku:

heroku run time rake assets:precompile --trace (clean first)

During deploy to heroku it takes around 10 minutes.

How do I figure out what the problem is here and fix it?

For reference I have tried all these:

• rake assets:precompile is slow (Tried turbo-sprockets-rails3 and it did not fix the issue)
• rake assets:precompile taking extremely long to complete (Tried YUI, no go)
• Why is assets:precompile so slow on Heroku? (We are on ruby 2)

We are on Rails 3.2.13, Ruby 2.0.0p353

Answer 1

You should try storing your assets in memcached/redis database so you only need to compile the ones that have changed in each release you deploy:

Setup a redis/memcached database w/ Heroku ( http://addons.heroku.com/ ) or use the one you already have

Configure an Asset cache store (via config/environments/production.rb ):

config.assets.cache_store = [ :redis_store,  {
  url: ENV['REDIS_URL'] || 'redis://127.0.0.1/0',
  namespace: 'assets'
}]

We have been able to get our asset precompilations times down < 30sec using this method from several minutes.