From: Dan Hinz <dhinz@...>
Date: 2006-01-17T06:01:19+09:00
Subject: Re: There's a deadlock in code in the PickAxe, and I'm not seeing	why:

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Hummmm, no help here, works fine for me.

Ruby 1.8.2, RH-8...

pridith:[2006.01.16-15:54]:time ./threads.rb
nil
1000000
32.200u 0.013x 0:32.59 99.1%    0+0k 0+0io 231pf+0w
pridith:[2006.01.16-15:56]:

-dwh-

On Mon, 2006-01-16 at 15:33, Dave Thomas wrote:

> The following code (form pg. 739) deadlocks with a large count. What  
> am I missing?
> 
> Cheers
> 
> 
> Dave
> 
> 
> 
> 
> require 'thwait'
> require 'sync'
> 
> class Counter
>    attr_reader :total_count
>    def initialize
>      @total_count = 0
>      @count_down = 0
>      @sync = Sync.new
>    end
>    def inc
>      @sync.synchronize(:EX) do
>        @total_count += 1
>        @count_down -= 1
>      end
>    end
>    def test_consistent
>      @sync.synchronize(:SH) do
>        fail "Bad counts" unless @total_count + @count_down == 0
>      end
>    end
> end
> 
> count = Counter.new
> waiter = ThreadsWait.new([])
> 
> # create 10 threads that each inc() 10,000 times
> 10.times do
>    waiter.join_nowait(Thread.new { 100_000.times do
>      count.inc
>      count.test_consistent
>    end })
> end
> 
> p waiter.all_waits
> p count.total_count
> 

-- 
I not only live each endless day in grief, but live each day
thinking about living each day in grief.
                                              -- C.S. Lewis

Daniel W. Hinz         Xerox Corp: XOG/SEBU/MCD/EIDC/ISM&D 
MS: 111-03J            e-mail:      dhinz@eng.mc.xerox.com
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