test.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'pg', '1.2.2'
end

$max_time = 2

Thread.new do
  begin
    while true
      Thread.list.each do |t|
        if (time = t["t"]) && time < Time.now - ($max_time*20)
          puts "Thread #{t} appears stalled"
        end
      end
      sleep 1
    end
  rescue => e
    STDERR.puts "Crashed monitor #{e}"
    exit 1
  end
end

$connections = Queue.new
30.times do
  $connections.push(PG::Connection.open(dbname: 'postgres'))
end

30.times do
  $connections.push(PG::Connection.open(dbname: 'discourse_development'))
end

$iterations = 0

(0...60).map do
  Thread.new do
    while true
      Thread.current["t"] = Time.now
      conn = $connections.pop
      conn.async_exec("select pg_sleep($1)", [rand * $max_time]).to_a
      $connections.push(conn)
      if ($iterations += 1) % 1000 == 0
        puts "#{$iterations} done"
      end
    end
  end
end.each(&:join)