原です。

In message "[ruby-list:15030] ConditionVariable (cv3.rb)"
    on 99/06/17, Shin-ichiro Hara <sinara / blade.nagaokaut.ac.jp> writes:

|test1.rb を改造した test-cv.rb（後掲）で、バッファサイズ３のパ
|イプに、送り手４スレッド受け手３スレッドでオブジェクトを通すも
|のです。停止するのは全ての受け手スレッドが 1000 個のオブジェク
|トを受け取った時とします。

一応 test-cv.rb です。無いよりましという程度で、必ずしもポイント
をついたいいテストプログラムというわけではありません。


幾つかパラメータをコマンドライン・パラメータに取るので、いろいろ
やってみると面白いですが、数字によって結構（数論的な？）動きがあ
ったりして、実は簡単に結論が出せません。cv3.rb はパラメータによ
らず比較的安定しているのは確かですが。もうちょっとちゃんとしたテ
ストプログラムが無いとこれ以上の効率や適正性の追求は難しそうです。

(バッファサイズ10送り手12受け手3で100回す例)
$ ruby test-cv.rb max10 s12 r3 100 cv3.rb

-------------^ test-cv.rb
#!/usr/local/bin/ruby
Thread.abort_on_exception = true

$sender_num = 4
$receiver_num = 3
$rtimes = 1000
$max = 3
$debug = 0

while para = ARGV.shift
  case para
  when /^n$/
    $no_signal_mutex = true
  when /^p$/
    $pass = true
  when /^d(\d)?$/
    $debug = ($1||1).to_i
  when /^\d+$/
    $rtimes = $&.to_i
  when /^max(\d+)$/
    $max = $1.to_i
  when /^r(\d+)$/
    $receiver_num = $1.to_i
  when /^s(\d+)$/
    $sender_num = $1.to_i
  else
    $o = para
  end
end

class Thread
  Num = [0]
  Obj2num = {Thread.current => 0}

  def Thread.start0
    Num[0] = Num[0]+1
    t = Thread.start {
      Thread.stop
      yield
    }
    Obj2num[t] = Num[0]
    t
  end

  def num
    Obj2num[self]
  end
  
  def Thread.num
    Obj2num[Thread.current]
  end
  alias to_s0 to_s
  def inspect; "#{Obj2num[self]}"; end
  def to_s; "#{Obj2num[self]}"; end
end

case $o
when /cv(\d+)/
  require $o
  $ver = $1.to_i
  $full = ConditionVariable.new
  $mutex = Mutex.new
  if $ver > 2
    $signal_param = $mutex unless $no_signal_mutex
  end
  $wait_param = $mutex
  $empty = ConditionVariable.new
when /^monitor/
  require $o
  $mutex = Monitor.new
  $full = $mutex.new_cond
  $empty = $mutex.new_cond
when /^mutex/
  require $o
  $mutex = Mutex.new
  $full = ConditionVariable.new($mutex)
  $empty = ConditionVariable.new($mutex)
else
  raise "can't get option: #$o"
end
print "TEST CONDITION VARIABLE <<< #{$o.upcase} >>>\n"
printf("Sender:%d, Receiver:%d (each receives %d times), Buffer:#$max\n",
       $sender_num, $receiver_num, $rtimes)
$queue = []

$rwaste = 0
$rwaste1 = 0
$swaste = 0
$swaste1 = 0

$snds = []
$rcvs = []
$snds_times = {}
$rcvs_times = {}

$sender_num.times do
  $snds.push Thread.start0 {
    n = 0
    $snds_times[Thread.current] = 0
    loop do
      $mutex.synchronize {
	k = 0
	while $queue.size >= $max
	  k += 1
	  if $wait_param
	    $full.wait($wait_param)
	  else
	    $full.wait
	  end
	  $swaste += 1 if k > 1
	end
	$swaste1 += 1 if k > 1
	$queue.push [n, Thread.num]
	if $queue.size >= 1 # == true
	  if $signal_param
	    $empty.signal($signal_param)
	  else
	    $empty.signal
	  end
	end
      }
      n += 1
      $snds_times[Thread.current] = n
      Thread.pass if $pass
    end
  }
end

$receiver_num.times do
  $rcvs.push Thread.start0 {
    n = 0
    $rcvs_times[Thread.current] = 0
    $rtimes.times do
      $mutex.synchronize {
	k = 0
	while $queue.size <= 0
	  k += 1
	  if $wait_param
	    $empty.wait($wait_param)
	  else
	    $empty.wait
	  end
	  $rwaste += 1 if k > 1
	end
	$rwaste1 += 1 if k > 1
	v = $queue.shift
	if $queue.size < $max
	  if $signal_param
	    $full.signal($signal_param)
	  else
	    $full.signal
	  end
	end
	printf("get %s (#%s->#%s)\n", v[0], v[1], Thread.num) if $debug > 0
      }
      n += 1
      $rcvs_times[Thread.current] = n
      Thread.pass if $pass
    end
  }
end

# START
Thread.critical = true
Thread::Obj2num.each do |t, n|
  t.wakeup if n > 0
end
Thread.critical = false

$rcvs.each do |t|
  VERSION.to_f >= 1.3 ? t.join : Thread.join(t)
end
$snds.each do |t|
  Thread.kill(t)
end

printf("Idling1: send =%2d, receive =%2d\n", $swaste1, $rwaste1)
printf("Idling2: send =%2d, receive =%2d\n", $swaste, $rwaste)
$snds.each do |t|
  printf("#%s sends %d times\n", t, $snds_times[t])
end
-------------$ test-cv.rb

以外と長かった。(^^;