Unicorn can't find gems?

Eric Wong normalperson at yhbt.net
Tue Jan 19 16:48:13 EST 2010

Steve Klabnik <steve at steveklabnik.com> wrote:
> Hello all. I've run into a strange problem with Unicorn, and Google
> couldn't help me out. Basically, I'm going to switch from Passenger to
> Unicorn for the next release of my Rails app. I installed it on my
> local machine, and it ran great. But then, as I was building my new
> server to deploy on, I ran into a snag.
> When I run 'unicorn_rails', I got a strange error. Here's the output
> of 'unicorn_rails -d' :
> $ unicorn_rails -d


> Exception `Gem::LoadError' at
> /opt/ruby-enterprise-1.8.7-2009.10/lib/ruby/site_ruby/1.8/rubygems.rb:280
> - can't activate rack (~> 1.0.0, runtime) for ["actionpack-2.3.5",
> "rails-2.3.5"], already activated rack-1.1.0 for ["unicorn-0.96.0"]
> Missing the Rails 2.3.5 gem. Please `gem install -v=2.3.5 rails`,
> update your RAILS_GEM_VERSION setting in config/environment.rb for the
> Rails version you do have installed, or comment out RAILS_GEM_VERSION
> to use the latest version installed.
> Exception `Errno::EAGAIN' at
> /opt/ruby-enterprise-1.8.7-2009.10/lib/ruby/gems/1.8/gems/unicorn-0.96.0/lib/unicorn.rb:436
> - Resource temporarily unavailable
> I, [2010-01-19T21:25:09.918670 #30184]  INFO -- : reaped
> #<Process::Status: pid=30185,exited(1)> worker=0
> Exception `Errno::ECHILD' at
> /opt/ruby-enterprise-1.8.7-2009.10/lib/ruby/gems/1.8/gems/unicorn-0.96.0/lib/unicorn.rb:454
> - No child processes
> And then it just repeats.
> I'm using ree both locally and on the server (as you can see), but I'm
> using it through rvm locally.
> Any idea what this might be?

Hi Steve,

Rails 2.3.x isn't compatible with Rack 1.1.0.  Unicorn depends on Rack
and since Unicorn is always loaded before Rails is, the Unicorn
dependency will always load the newest version of Rack on the system.

Uninstalling Rack 1.1.0 for now should fix things, just keep Rack 1.0.1

I'll add this to the FAQ for now, not sure if there's a sane solution
for it...

Eric Wong

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