Ruby-Debug19 on Ruby-1.9.3-Preview1

Rails with ruby-debugger throw 'Symbol not found: _ruby_current_thread (LoadError)'

UPDATE:

Looks like you only need to put this in your gemfile:

gem "debugger"

and now works.

Old article follows

====================================

Jerome is correct, but lacking in the details. Here is the blow by blow, taken from this https://gist.github.com/1331533, in particular thanks to andrewroth's post. I've tested this as of the time of this post. One hopes that the changes will be deployed somewhere standard soon.

Installing ruby debugger on ruby 1.9.3-p125: 

export PATCH_LEVEL=`ruby -e 'puts RUBY_PATCHLEVEL'`
export RVM_SRC=$HOME/.rvm/rubies/ruby-1.9.3-p$PATCH_LEVEL/include/ruby-1.9.1
gem install archive-tar-minitar
gem install ruby_core_source -- --with-ruby-include=/$RVM_SRC
export RVM_SRC=$HOME/.rvm/rubies/ruby-1.9.3-p$PATCH_LEVEL/include/ruby-1.9.1/ruby-1.9.3-p$PATCH_LEVEL

wget http://rubyforge.org/frs/download.php/75415/ruby-debug-base19-0.11.26.gem
wget http://rubyforge.org/frs/download.php/63094/ruby-debug19-0.11.6.gem
wget http://rubyforge.org/frs/download.php/75414/linecache19-0.5.13.gem
gem install linecache19-0.5.13.gem -- --with-ruby-include=/$RVM_SRC
# if that step failed, and you are running OSX Lion, then following this post can help you: 
# http://stackoverflow.com/questions/8032824/cant-install-ruby-under-lion-with-rvm-gcc-issues
# this happens if you recently installed xcode from the app store. 
# bizarrely, for me I had to do this: ln -s /usr/bin/gcc /usr/bin/gcc-4.2
gem install ruby-debug-base19-0.11.26.gem -- --with-ruby-include=/$RVM_SRC

Then edit Gemfile: 

gem 'linecache19', '0.5.13', :path => "~/.rvm/gems/ruby-1.9.3-p#{RUBY_PATCHLEVEL}/gems/linecache19-0.5.13/"
gem 'ruby-debug-base19', '0.11.26', :path => "~/.rvm/gems/ruby-1.9.3-p#{RUBY_PATCHLEVEL}/gems/ruby-debug-base19-0.11.26/"
gem 'ruby-debug19', :require => 'ruby-debug'

Then install: 

bundle install

ruby-debug with Ruby 1.9.3?

Update (April 28, 2012)

Try the new debugger gem as a replacement for ruby-debug.

^{(credit to @ryanb)}

Update (March 2, 2012)

Installation of linecache19 and ruby-debug-base19 can be easily done with:

bash < <(curl -L https://raw.github.com/gist/1333785)

^{(credit to @fredostarr)}

Original answer

Have you looked at ruby-debug19 on ruby-1.9.3-preview1?

Here's a temporary solution:
http://blog.wyeworks.com/2011/11/1/ruby-1-9-3-and-ruby-debug

Excerpt from the site:

First download linecache19-0.5.13.gem and
ruby-debug-base19-0.11.26.gem from
http://rubyforge.org/frs/?group_id=8883, then …
$ gem install linecache19-0.5.13.gem 
Building native extensions.  This could take a while...
Successfully installed linecache19-0.5.13
1 gem installed
$ gem install ruby-debug-base19-0.11.26.gem -- --with-ruby-include=/Users/santiago/.rbenv/source/ruby-1.9.3-p0  
Building native extensions.  This could take a while...
Successfully installed ruby-debug-base19-0.11.26
1 gem installed
$ irb
irb(main):001:0> require 'ruby-debug'
=> true

Rails 3.2.0 rspec debugger not working

Stick this in your Gemfile:

# one-liner to install these properly: bash < <(curl -L https://raw.github.com/gist/1333785)
gem 'linecache19', '0.5.13'
gem 'ruby-debug-base19', '0.11.26'

You'll need to run that one-liner in order for bundler to pick up the proper gems.

EDIT: I forgot to link to the posts I used to get debugging working:

ruby-debug with Ruby 1.9.3?
ruby-debug19 on ruby-1.9.3-preview1

Rails 3.1 and Ruby 1.9.3p125: ruby-debug19 still crashes with Symbol not found: _ruby_threadptr_data_type

A fork of ruby-debug just called 'debugger' now exists that incorporates many of the fixes people had been deploying on top of ruby-debug19, so you should be able to just change your Gemfile to

gem 'debugger'

... and off you go.

Cannot use ruby-debug19 with 1.9.3-p0?

UPDATE: ruby-debug19 is not maintained anymore. This question and my answer have become irrelevant, it's far easier to use the 'debugger' gem instead.

See Debugging in ruby 1.9

I also ran into this, and found the solution in Ruby 1.9.3 and ruby-debug. You need to install not-yet-officially-released versions of ruby-debug-base19 and linecache19. The currently released versions indeed cause the exception you had.

Use this gist.

#To install ruby-debug on Ubuntu ruby-1.9.3 you need to download from http://rubyforge.org/frs/?group_id=8883

linecache19-0.5.13.gem 
ruby_core_source-0.1.5.gem 
ruby-debug19-0.11.6.gem 
ruby-debug-base19-0.11.26.gem

#Then in your console

export RVM_SRC=/your/path/to/ruby-1.9.3
# Note, your source path should be something like /home/user/.rvm/src/ruby-1.9.3-p0

gem install archive-tar-minitar
gem install ruby_core_source-0.1.5.gem -- --with-ruby-include=/$RVM_SRC
gem install linecache19-0.5.13.gem -- --with-ruby-include=/$RVM_SRC
gem install ruby-debug-base19-0.11.26.gem -- --with-ruby-include=/$RVM_SRC
gem install ruby-debug19-0.11.6.gem -- --with-ruby-include=/$RVM_SRC

railstutorial where is debug information coming from

Interesting question! I searched all library sources of a rails project for 'hash-with-ivars' and only a single place came up: the psych ruby library for (de-)serializing arbitrary objects to and from YAML. Specifically, these are links to the source code for reading and writing this YAML structure.

In Chapter 7 of the Rails Tutorial, this output comes out as the output of the debug(params) command that you are instructed to put in a template. The debug command apparently calls the psych library to show a readable representation of the object (params in this case).

Now, params - the universal Rails data structure to hold parameters passed from URLs or forms - is an object that behaves like a Hash but is not pure hash: it is an instance of class ActionController::Parameters which is a subclass of Hash, let's see the class definition:

module ActionController
  # ...
  class Parameters < ActiveSupport::HashWithIndifferentAccess
    # ...
  end
end

while HashWithIndifferentAccess is a direct subclass of Hash.

As a subclass of Hash, the params object can hold other data besides the hash itself and this is what psych actually supports when trying to print the object in a readable form. Besides printing all the hash elements (under the elements key), it tries to also list all instance variables of the object and prints it under the ivars key.

So, all in all, this debug print simply says that the object debugged is an instance of the ActionController::Parameters class, which is a subclass of Hash, that besides it's hash elements has also a @permitted instance variable defined and it is currently set to false. The two elements, by the way, the controller and action are parameters used internally by Rails for routing.

When you look into the source of the class again, you will indeed find the @permitted variable right in the constructor:

class Parameters < ActiveSupport::HashWithIndifferentAccess
  # ...
  def initialize(attributes = nil)
    super(attributes)
    @permitted = self.class.permit_all_parameters
  end
end

Finally, from the documentation we can conclude that the @permitted variable holds the state of the params permission. I.e. it is set to true after the params are permitted by using the permit method:

permitted = params.require(:person).permit(:name, :age)
permitted.permitted? # this prints out the @permitted instance variable
# => true

Update: why the RailsTutorial's debug output differs

The debug output at the RailsTutorial differs a bit - it does not print ivars. Why? It is because the feature for serializing hash-with-ivars was added to the psych gem in its version 2.0.9. The psych gem is now a part of the Ruby standard library and this particular version of it has been added to the stdlib 2.3.0 preview1 version.

So, the mysteriously different output has a simple explanation: the RailsTutorial author most probably used ruby 2.2 or earlier when writing the book and this ruby version did not display instance variables in the Hash debug output yet. Actually, there are hints in the tutorial that suggest that the author used ruby 2.1.5.

Why would `rvm install ruby-2.1.0` install preview1?

Silly clarification question (and I would post it as a comment if I had enough reputation), but have you updated RVM lately?

rvm get stable (or if you want to live on the edge, rvm get head) would, I expect, update the internal list of released ruby versions.

Why is my pry-byebug package giving so much output when a command executes some error?

so I recently just used rvm to download and set my default version of Ruby to 2.6.5. The verbose output has now ceased entirely.

Error installing debugger: Failed to build gem native extension with ruby-1.9.3-p362

I ran into same issue. I tried:

bundle update debugger

My Gemfile had this:

gem 'debugger'

And it worked, I did not have to change Gemfile. Output of bundle shows something like this

...

Installing debugger-ruby_core_source (1.1.6)

Installing debugger-linecache (1.1.2) with native extensions

Installing debugger (1.1.4) with native extensions