From: "James F.Hranicky" <jfh@...>
Date: 2002-08-29T01:04:44+09:00
Subject: Native Threads (was Re: [Cleanup?] Int vs Long)

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On Thu, 22 Aug 2002 19:06:15 +0900
Michal Rokos <m.rokos@sh.cvut.cz> wrote:

> 	As I calculated the space needed for this new lock, it could add
> 	about 5 pointers size to every Ruby object, that means: doubles
> 	memory needs! (Current std. Ruby object is about 5 pointers as
> 	well) I'm not sure wether it is acceptable.
> 
> 	Also this could bring a lot of deadlocks and I'm not sure if it
> 	is suitable for eval and parsing part.
> 	====================================
> 
> 	If you will have just 1 global lock, I don't see any benefit of
> 	bringing native threads in.
> 	
> 	So the project has stopped because of lack of discussion.

Hmmm...if it were possible to have a hash that atomically raised an
exception if the setting of a key was done twice, but allowed for
deletes:

	LOCKS = ImmutableKeyHash.new
	LOCKS[obj.id] = 1
	LOCKS[obj.id] = 1 # -> Exception thrown
	LOCKS.delete(obj.id)
	LOCKS[obj.id] = 1

we could keep a list of locked objects, and set it up like so:

    f = File.open("/tmp/foo", "w")
    1.upto(1) { |i|

        ts << NThread.new {

            NThread::Lock(f) { |f|
                f.puts("#{i}")
                f.close
            }
	}
    }

    ts.each { |t|
        t.join
    }

I don't know how feasible such a hash would be.

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