[Octave-bug-tracker] [bug #38905] Memory Leak in openmpi_ext

[Carlo de Falco]

Update of bug #38905 (project octave):

                  Status:                    None => Need Info              

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Follow-up Comment #2:

Riccardo just posted this comment:


Carlo,
I do not think this is a bug.
It is just that ... since openmpi_ext is a prototype it needs more functions
(like MPI_Isend and MPI_IRecv).
When the master has lots of slaves "blocked" , the memory using lots of
matrixes will become exhausted.
One solution would be to implement non - blocking messages and to "probe"
about them.
Micheal Creel pings at messages to gather as much as possible. Cleary this
might be improved.
What do you think? Am I clear?
Very bests
Riccardo



Riccardo,

Unfortunately replying to messages on this tracker by 
hitting "reply" in your mail client does not work, you 
need to click on the link that takes you to the tracker
and write the answer there directly.

I am not completely sure I understand why you
expect blocking communications to use more memory
than non-blocking ones.

If I understand correctly, when a blocking send/receive
is issued the program should wait until the data transmission
is completed before proceeding to the next instruction.


Therefore, upon exit from the MPI_{Send,Receive} function 
there is no need to keep any of the buffers used for communication and they
should be cleared.

And actually that is the way the code in openmpi_ext is implemented, all local
memory is allocated via the 
OCTAVE_LOCAL_BUFFER macro and should be therefore cleared
upon exit.

So I don't see why you expect that the master may have 
"lots of slaves blocked" as far as I understand each process
should be able to have only one pending communication 
at each time ...

Can you explain in more detail what you think is actually happening?

c. 

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