From: Francis Cianfrocca <garbagecat10@...>
Date: 2006-06-21T05:18:12+09:00
Subject: Re: C Threads and Ruby

------=_Part_2402_7411642.1150834687765
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

>>>That is not true, it is completely possible to use an OS level
mutex/critical section etc, from inside a "green" Ruby thread. It will
block all Ruby threads which is not very nice, but I do not know of a
better solution.<<<

That's why I said you can't do it ;-). It indeed is not very nice unless
you're very disciplined about how you design your synchronization sets. (And
one of my pet peeves is that most people have no clue how to do this right.)
Bad possibility is crummy performance. Worse yet is deadlocks, which are
possible if the native code relies on something else Ruby is doing.

On 6/20/06, Patrick Hurley <phurley@gmail.com> wrote:
>
> On 6/20/06, Francis Cianfrocca <garbagecat10@gmail.com> wrote:
> > Patrick: given your proposal for an event queue filled by native threads
> in
> > C and consumed by a Ruby thread, notice that there is no mutex that
> works
> > between native threads and Ruby threads. Your example of "signalling" by
> > changing the value of an integer probably works because on an Intel chip
> > (you said you did this on Windows), it only takes one memory-bus cycle
> to
> > change the value of a 32-bit integer, so you can get away without a
> mutex. I
> > doubt this would work with a more complex data structure.
>
> That is not true, it is completely possible to use an OS level
> mutex/critical section etc, from inside a "green" Ruby thread. It will
> block all Ruby threads which is not very nice, but I do not know of a
> better solution.
>
> I used a system mutex (actually a CriticalSection) in both threads --
> yes it blocks ruby, but only long enough to read the memory. It would
> be better  if the Ruby C API provide a thread safe wait for non-native
> threads -- but this does work and is completely thread safe even if I
> were not doing an atomic operation (for example working off a linked
> list).
>
> pth
>
>

------=_Part_2402_7411642.1150834687765--