Testcase to reproduce kqueue crash with thin on eventmachine 1.0.8

em-108-arm-kqueue-writer-failed-testcase.rb

#!/usr/bin/env ruby
begin
  require 'bundler/inline'
rescue LoadError => e
  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
  raise e
end

gemfile(true) do
  source 'https://rubygems.org'
  gem "eventmachine", "1.0.8"
  gem "thin", "1.6.3"
end

EM.kqueue

class DeferrableBody
  include EventMachine::Deferrable

  def call(body)
    body.each do |chunk|
      @body_callback.call(chunk)
    end
  end

  def each &blk
    @body_callback = blk
  end

end

class AsyncApp
  AsyncResponse = [-1, {}, []].freeze

  def call(env)
    body = DeferrableBody.new
    EventMachine::next_tick { env['async.callback'].call [200, {'Content-Type' => 'text/plain'}, body] }

    EventMachine::add_timer(1) {
      body.call ["Woah, async!\n"]

      EventMachine::next_tick {
        body.call ["Cheers then!"]
        body.succeed
      }
    }
    AsyncResponse
  end
end

Thin::Server.start('127.0.0.1', 3000, AsyncApp.new)

Usage

On a recent Mac OS X system (tested on 10.11 (15A263e) / ruby 2.2.3p173 x86_64) run:

# start a thin server on port 3000
ruby em-108-arm-kqueue-writer-failed-testcase.rb
# hit it hard with apache bench from another terminal
ab -r -c 150 -n 15000 http://127.0.0.1:3000/

It should crash with an error (might require a couple of tries, just rerun ab):

libc++abi.dylib: terminating with uncaught exception of type std::runtime_error: arm kqueue writer failed on 32681: Bad file descriptor