Question

I’m new to Ruby on Rails.

I ran the following in a terminal when I was going through creating a blog tutorial with Rails:

$ rails blog
[BUG] cross-thread violation on rb_gc()
(null)

Abort trap

How do I determine what this error message means and how to fix it?

$ gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.3.7
  - RUBY VERSION: 1.8.7 (2010-06-23 patchlevel 299) [i686-darwin10]
  - INSTALLATION DIRECTORY: /opt/local/lib/ruby/gems/1.8
  - RUBY EXECUTABLE: /opt/local/bin/ruby
  - EXECUTABLE DIRECTORY: /opt/local/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86-darwin-10
  - GEM PATHS:
     - /opt/local/lib/ruby/gems/1.8
     - /Users/sunpech/.gem/ruby/1.8
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
     - :sources => ["http://rubygems.org/", "http://gems.github.com"]
  - REMOTE SOURCES:
     - http://rubygems.org/
     - http://gems.github.com

UPDATE

I did some fiddling and I’m not getting the error message anymore. But I do notice that my environment is running a different path of Ruby now.

$ gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.3.5
  - RUBY VERSION: 1.8.7 (2009-06-12 patchlevel 174) [universal-darwin10.0]
  - INSTALLATION DIRECTORY: /Library/Ruby/Gems/1.8
  - RUBY EXECUTABLE: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby
  - EXECUTABLE DIRECTORY: /usr/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - universal-darwin-10
  - GEM PATHS:
     - /Library/Ruby/Gems/1.8
     - /Users/sunpech/.gem/ruby/1.8
     - /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
     - :sources => ["http://rubygems.org/", "http://gems.github.com"]
  - REMOTE SOURCES:
     - http://rubygems.org/
     - http://gems.github.com

This seems to imply that I have multiple installs of Ruby on my Mac box. One in /opt/local/bin/ and /usr/bin/. I think the former came from a MacPorts install, and the latter is what came with my system (possibly upgraded).

Answer 1

The problem was that I had multiple installs/paths of ruby on my system. Mac OS X Snow Leopard comes with ruby pre-installed I believe. I made the mistake of using MacPorts to install a newer version, right alongside.

I fixed the problem by:

1. Uninstalling the version of ruby from Macports
2. Installing Ruby Version Manager, aka rvm, to help me manage multiple ruby installs. (optional, but recommended)

I also posted this on Ruby on Rails Talk. See Error: cross-thread violation on rb_gc()