Error when run server rails 2.3.5 with memcached - ruby-on-rails

Question

I use ruby version 1.8.7, gem version 1.3.5, rails version 2.3.5 and memcache. I get this error when I run server
phuongnm-lap:~/trunk/hurricane$ ruby script/server
=> Booting Mongrel
=> Rails 2.3.5 application starting on http://0.0.0.0:3000
/home/asiantech/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.11.2/lib/bundler/runtime.rb:77:in `require': /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/get_process_mem-0.2.0/lib/get_process_mem.rb:60: undefined (?...) sequence: /(?<value>(\d*\.{0,1}\d+))\s+(?<unit>\w\w)/ (SyntaxError)
from /home/asiantech/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.11.2/lib/bundler/runtime.rb:77:in `require'
from /home/asiantech/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.11.2/lib/bundler/runtime.rb:72:in `each'
from /home/asiantech/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.11.2/lib/bundler/runtime.rb:72:in `require'
from /home/asiantech/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.11.2/lib/bundler/runtime.rb:61:in `each'
from /home/asiantech/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.11.2/lib/bundler/runtime.rb:61:in `require'
from /home/asiantech/.rvm/gems/ruby-1.8.7-p374/gems/bundler-1.11.2/lib/bundler.rb:99:in `require'
from ./script/../config/boot.rb:41:in `load_gems'
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/rails-2.3.5/lib/initializer.rb:164:in `process'
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `send'
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `run'
from /home/asiantech/trunk/hurricane/config/environment.rb:34
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require'
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require'
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:521:in `new_constants_in'
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require'
from /home/asiantech/trunk/hurricane/vendor/bundle/ruby/1.8/gems/rails-2.3.5/lib/commands/server.rb:84
from script/server:3:in `require'
from script/server:3
please help me!

Answer 1

Your ruby version is too old for the get_process_mem gem to run. The gem uses a complex regular expression to parse information from /proc files on your linux server. However, ruby 1.8.7 does not support such complex regexp yet.
You can see for yourself in irb. In ruby 1.8.7 the match fails:
"aaa" =~ /(?<value>(\d*\.{0,1}\d+))\s+(?<unit>\w\w)/
# => SyntaxError: compile error
# => (irb):1: undefined (?...) sequence: /(?<value>(\d*\.{0,1}\d+))\s+(?<unit>\w\w)/
whereas under ruby 2.2 it works ok (does not return anything in this test case, but more importantly, does not fail with error):
"aaa" =~ /(?<value>(\d*\.{0,1}\d+))\s+(?<unit>\w\w)/
# => nil
You have a few options now:
Upgrade to a newer ruby (and rails) if you can, you won't have to solve these elderly code-related problems and won't be using an unsupported ruby/rails version any more, but nevertheless this is rather a cumbersome process.
Get rid of the get_process_mem gem. You can see the same info, i.e. the memory consumed by the process, using command line utilities, without needing to install any gem. Try the top or htop commands for example.