gistfile1.rb

require "rubygems"
require "eventmachine"
require "fileutils"

module Handler
  def file_modified
    raise "iamfail, hear me roar"
    puts "#{path} modified"
  end

  def file_moved
    puts "#{path} moved"
  end

  def file_deleted
    puts "#{path} deleted"
  end

  def unbind
    puts "#{path} monitoring ceased"
  end
end

FileUtils.touch("/tmp/fwtest")
EM.kqueue = true
EM.run do
  watcher = EM.watch_file("/tmp/fwtest", Handler)
  raise "failz"
  Kernel.system("echo 'failtime' >> /tmp/fwtest")
  EM.add_timer(1) do 
    watcher.stop_watching
    EM.stop
  end
end

gistfile2.txt

(gdb) run ./filewatch_test.rb
Starting program: /opt/local/bin/ruby ./filewatch_test.rb
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
Reading symbols for shared libraries . done
Reading symbols for shared libraries .... done
/tmp/fwtest monitoring ceased

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000022
0x00007fff84719f80 in std::_Rb_tree_increment ()
(gdb) bt
#0  0x00007fff84719f80 in std::_Rb_tree_increment ()
#1  0x00000001003bbce6 in EventMachine_t::~EventMachine_t ()
#2  0x00000001003b33d2 in evma_release_library ()
#3  0x00000001003c3129 in t_release_machine ()
#4  0x0000000100028e10 in rb_call0 ()
#5  0x000000010002914b in rb_call ()
#6  0x00000001000226c1 in rb_eval ()
#7  0x00000001000257dc in rb_eval ()
#8  0x0000000100025258 in rb_eval ()
#9  0x0000000100028d33 in rb_call0 ()
#10 0x000000010002914b in rb_call ()
#11 0x000000010002252b in rb_eval ()
#12 0x0000000100025c08 in rb_eval ()
#13 0x000000010003505b in ruby_exec_internal ()
#14 0x0000000100035098 in ruby_exec ()
#15 0x00000001000350c0 in ruby_run ()
#16 0x0000000100000ee4 in main ()
(gdb)