From: pmr16366@...
Date: 2007-01-04T02:40:07+09:00
Subject: Re: Memory Leak Madness

I think you said you are using Windows/Ms SQL Server.
The ADO driver leaks memory like you wouldnt beleive.
In my rails app I switched to odbc and it runs much better.


khaines@enigo.com wrote:
> On Thu, 4 Jan 2007, Brandon Casci wrote:
>
> > Do you mean this by locking?
> >
> > @mutex.synchronize do
> >  @myarray << station
> > end
> >
> > Becuase I do that in two spots, although I do .clear out that
> > frequently.
>
> Do you have situations where you end up with a lot of threads?  Do you
> then have a lot of threads all using the same Mutex?  There's an issue
> with the way Ruby handles the memory allocated to an array when values are
> shifted off of it.  In short, Mutex uses an array to manage the queue of
> waiting threads.  It pushes onto it and shifts them off of it, and if you
> have a lot of threads, you will see what seems to be inexplicable memory
> usage as a consequence.  Also be aware that if you use shift() on arrays
> elsewhere, your arrays are using more memory than you think.
>
> The current best fix is to use the fastthread library if you can.  It
> replaces the Ruby threading support items like Mutex with much faster C
> versions.
>
> If, for whatever reason, you can't do this, you can override the
> definitions of the Thread lock() and unlock() methods to use unshift and
> pop instead of push and shift for placing items into the queue and taking
> them off.  This doesn't hold a candle to all that's being done with
> fasthread, but it does eliminate a bad RAM usage issue if you really can't
> use fasthread for whatever reason.
>
> Something like this:
>
> class Thread
>
>    def lock
>      while (Thread.critical = true; @locked)
>        @waiting.unshift Thread.current
>        Thread.stop
>      end
>      @locked = true
>      Thread.critical = false
>      self
>    end
>
>    def unlock
>      return unless @locked
>      Thread.critical = true
>      @locked = false
>      begin
>        t = @waiting.pop
>        t.wakeup if t
>      rescue ThreadError
>        retry
>      end
>      Thread.critical = false
>      begin
>        t.run if t
>      rescue ThreadError
>      end
>      self
>    end
> 
> end
> 
> 
> Kirk Haines