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

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* David(Dedi) Bachar

 
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