Gave a shot to the new Bundler 1.4.0RC1 during the weekend and found out it now supports gem installation in parallel. To invoke you need to pass
--jobs parameter with number of threads you want it to run – for me the best performance was achieved by specifying the number physical CPU cores.
I've tested on theapp. In my case (CPU with 2-core i7 with HT) the speedup was 50%. I've also tried with a number greater than the number of physical cores but the performance was 15%-20% worse.
➜ appfab git:(master) bundle --version Bundler version 1.3.5 ➜ appfab git:(master) time bundle install --path=vendor/ 483.44 real 126.23 user 39.96 sys
gem update bundler —pre ➜ appfab git:(master) bundle --version Bundler version 1.4.0.rc.1 ➜ appfab git:(master) time bundle install --jobs 2 --path=vendor/ 234.65 real 136.37 user 42.40 sys