From: "Florian Groß" <florgro@...>
Date: 2006-01-23T06:24:49+09:00
Subject: Re: Debugging endless loops

Alexey Verkhovsky wrote:

> Say, we have a Ruby app going into an endless loop (or perhaps a thread 
> deadlock) mode. Let us further assume that it happens in production and 
> you don't know how to reproduce it anywhere else. How would you debug this?
> 
> But what do I do if it's Ruby?

This might work and give you a remote debugging back door. I'm just not 
sure if it will survive deadlocks:

require 'breakpoint'
Breakpoint.activate_drb

Thread.new do
   Thread.current.priority = 100
   loop do
     begin
       breakpoint
     rescue Exception
     end
   end
end

You can then connect to your application with breakpoint_client.

You'll need the ruby-breakpoint library which is available from 
http://ruby-breakpoint.rubyforge.org/

-- 
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