On 5/27/08, Greg Ewing <[EMAIL PROTECTED]> wrote: > Travis Oliphant wrote: > > > Obviously, if you haven't provided a Py_buffer structure to fill in, then > you are only asking to lock the object's buffer from other access. > > > > What's the use case for that? Why would you ever want > to lock an object if you don't intend to access it? >
Well, iff we already accessed the object, had stored the raw memory pointer, and hold a reference to it, and now we want other thread to operate on the raw memory, does not make sense to just lock the object? In the context of MPI communication, I believe I have a use case, using something called persistent communication requests. You emit a Comm.Recv_init() call with the pointer to the buffer receiving the message (then you have to ask the object for the buffer pointer). The Comm.Recv_init() returns a 'Prequest' instance (persistent request), but the actual communication does not initiate until you call Prequest.Start(). Then when you initiate the communication, we should lock the object until the communication finalizes, because then we could release the GIL but protect the raw memory from other accesses. -- Lisandro Dalcín --------------- Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC) Instituto de Desarrollo Tecnológico para la Industria Química (INTEC) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) PTLC - Güemes 3450, (3000) Santa Fe, Argentina Tel/Fax: +54-(0)342-451.1594 _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
