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Subject: Re: [OMPI users] Communication between objects on different nodes
From: Alexandru Blidaru (alexsb92_at_[hidden])
Date: 2010-07-23 11:55:31


I also forgot to add that one of the bonus requirements for my project is to
be able to use it with whatever number of slave nodes, which i think makes
the whole deal a lot more complicated.

On Fri, Jul 23, 2010 at 11:48 AM, Alexandru Blidaru <alexsb92_at_[hidden]>wrote:

> Hey guys,
>
> I need to write an implementation of a 4D array with a variable 4th
> dimension based on where in 3D you are. So it's basically like a normal
> rectangular prism, except for each unit it might have a variable number of
> values. The program is also supposed to communicate by sending ghost nodes
> between each slice, in order for the actual data-modifying code to work. The
> data-modifying code is to be added by others depending on what they need to
> do with this 4d array.
>
> So what I am really asking is how does MPI work when you have different
> objects on different computers and you try sending stuff between the
> objects?
>
> Just some explanations for my code, which is attached, in case you can give
> some code-specific tips:
>
> - Nx2, Nz2, Ny2 are the lengths of the big prism
> - DOFArr holds how many values there will be for each space in 3D, by
> transforming the 3D coordinates into 1D this way: index of
> DOFArr=i+Nx*j+Nx*Ny*k
> - So the way i was thinking of doing is for the master to get the big
> array, and split into relatively equal parts and send each part to a node.
> The node would then do whatever it had to do, send ghost nodes to its
> neighbors, maybe do whatever it had to do again and in the end it would send
> everything back to the master node, which would take the pieces of array and
> put them together.
>
>
> I am also a bit confused with when do you have to call MPI_Finaliza(). I
> mean, for it to run, the program required me to put it into the constructor,
> and if I call print() at the and of the constructor, it would tell me this:
>
> job aborted:
>
> rank: node: exit code[: error message]
>
> 0: C7June2010: 123
>
> 1: C7June2010: -1073740777: process 1 exited without calling finalize
>
> 2: C7June2010: -1073740777: process 2 exited without calling finalize
>
>
> If i would place it after Finalize() nothing would show when i run the exe.
>
>
> I just finished grade 12, and got a summer job at a research lab, and this
> is my project. Thanks a lot for your help.
>
> Alex
>