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From: Bachar Dedi [Netanya] (david.bachar_at_[hidden])
Date: 2010-08-08 01:20:35


Hello,

My name is David and I am a programmer who uses MPI.net. One of my
application needs is to pass a large amount of bytes (a 60 MB file)
between the ranks.
I recently encountered a problem , I'm getting the one of follow
exception
 "AccessViolationException: Attempted to read or write protected memory.
This is often an indication that other memory has been corrupted."
Or
job aborted:
[ranks] message

[0-20] terminated

[21] fatal error
Fatal error in MPI_Iprobe: Internal MPI error!, error stack:
MPI_Iprobe(125)..................: MPI_Iprobe(src=MPI_ANY_SOURCE,
tag=MPI_ANY_TAG, MPI_COMM_WORLD, flag=0x00000000002AE428,
status=0x00000000002AE410) failed
MPIDI_CH3I_Progress_shm(93)......: shared memory read progress failed
MPIDI_CH3I_SHM_read_progress(312): shared memory read progress unable to
handle incoming packet
MPIDI_CH3U_Handle_recv_pkt(184)..: received unknown packet type
(type=12554704)
 [22-24] terminated

Or another exception regarding MPI_ALLOC_MEM.

I'm trying to see if I understand the memory allocation process, and the
problem and to see if there is any solution.

If I understand correctly when I use the send message, the MPI
communicator actually allocates an unmanaged memory on the stack and
copies the managed data into it and then when I receive the data on the
receiver rank it is copied into a new managed memory block and then the
unmanaged memory (in the sender process) is freed. Is what I described
so far correct?

Now the important issue is how do I try and solve the problem. I didn't
quite understand why the allocated memory was not enough and how can I
guarantee it will be enough in my case. Or why there is a try to access
outside of the memory borders.
Another question is: does this problem occur only with large byte
arrays? If I will change my message to contain a constant size byte
array (e.g. byte[50000]) will this solve the problem?
        

Thank you in advance,
David

* Mobile: 054-9981887
* Office: 09-8864730
* David(Dedi) Bachar <mailto:david.bachar_at_[hidden]>

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