The issue(s) you are experiencing could be due to 3 things:
- The version of Ruby you are using
- The use of the SystemTimer gem with Ruby 1.9
- The JSON gem
I've elaborated below...
The first thing I would suggest is to upgrade your version of Ruby 1.9. The latest stable is:
ruby 1.9.2p180 (2011-02-18 revision 30909)
I would highly recommend using Ruby Version Manager (RVM) to install and manage Rubies.
In terms of using the JSON gem, have a look at:
http://ruby.about.com/od/tasks/a/The-Json-Gem.htm
To quote:
On Ruby 1.8.7, you'll need to install a gem. However, in Ruby 1.9.2, the json gem is bundled with the core Ruby distribution. So, if you're using 1.9.2, you're probably all set. If you're on 1.8.7, you'll need to install a gem.
Before you install the JSON gem, first realize that this gem is distrubuted in two variants. Simply installing this gem with gem install json will install the C extension variant. This requires a C compiler to install, and may not be available or appropriate on all systems. Though if you can install this version, you should.
If you can't install the C extension version, you should gem install json_pure instead. This is the same gem implemented in pure Ruby. It should run everywhere that Ruby code runs, on all platforms and on a variety of interpreters. However, it's considerably slower than the C extension version.
Edit:
Looks like you should avoid using the SystemTimer gem with Ruby 1.9. See this for more info: http://isitruby19.com/systemtimer
To quote a comment made on that page by Phillipe:
I am the (co)-author of this gem. Short story : Using this gem in Ruby 1.9 is useless and does not make any sense!
System Timer is trying to work around some limitation of the "green thread" model used in Ruby 1.8 (MRI). See http://ph7spot.com/musings/system-timer for more details.
It is then irrelevant in a Ruby 1.9 which abandoned the green thread model and embraced native threads (kind of since there is still a global interpreter lock).
Cheers,
- Philippe