Handle the USR1 signal by printing backtraces

backtrace_printer

#!/usr/bin/env ruby
puts "PID: #{$$}"

trap("USR1") do
  @dump = true
end

t = Thread.new do 
  loop do
    print '<'
    sleep 1
  end
end

f = Thread.new do 
  loop do
    f = rand(10) + rand(10) + rand(10) + rand(10)
    sleep 0.003
  end
end

printer = Thread.new do
  loop do
    if @dump
      Thread.list.each do |t|
        puts t.inspect
        puts t.backtrace
      end
      @dump = false
    else
      sleep 0.5
    end
  end
end

printer.join

Cool! Signal handling FTW!