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Re: Python plugin API locking (patch)
A Dom, 2003-10-05 às 16:45, Michael Edenfield escreveu:
> * Marko Kreen <marko@l-t.ee> [031003 18:25]:
> > On Fri, Oct 03, 2003 at 10:34:41PM +0100, Gustavo J. A. M. Carneiro wrote:
> > > This patch should protect all plugin API functions with a global
> > > recursive mutex.
> >
> > Thats a cool patch, but it seems its not enough...
> >
> > You protect plugins from each other, thats cool, but at the
> > moment plugin can run gtk signal loop, its not enough: now also
> > xchat C code should go through locks, that means that locks
> > should be in xchat core code. Thats what made me so worried...
> >
> > (Think of one thread having plugin lock and calling xchat
> > functions, another thread running gtk.mainloop - now there
> > are 2 threads inside xchat core)
>
> The correct solution (the only one that I think will work completely) is
> to ultimately lock *resources* at a low level. The locks need to be, as
> you said, placed throughout the XChat core code. The code needs to lock
> thinks like output buffers and global data lists, not whole plugins.
>
> The benefits of this are obvious: not only does it remove much of the
> locking issues with plugins, but it permits the code code itself to
> thread more. Right now a single thread is spawned per server and that's
> basically it. For example, the optimal way to do a dns lookup is to
> spawn a dns lookup thread -- but that requires locking the output
> buffers on the sessions.
While running under gdb, I have never even noticed xchat spawning
threads. Are you sure xchat core uses threads at all?
>
> The downside, of course, is that it's a *ton* of work. But the locking
> itself can be done piecemeal. Chase down global resources and start
> adding locking code to them one at a time. Having seen other
> applications go through this (and been writing some of them), it's a
> pain in the ass. But ultimately it's the only way to do it right.
Yes, I agree with you, but I'm not willing to do the huge amount of
work to get this right. Especially since I don't understand at all the
xchat internals, since I was looking at the code for the first time.
--
Gustavo João Alves Marques Carneiro
<gjc@inescporto.pt> <gustavo@users.sourceforge.net>
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