[mvapich-discuss] dynamic process management (DPM) questions

[Krishna Chaitanya]

Bryan,
           I think the problem you are seeing here is because the client
process is not getting the right port information, even though you are
passing it as a command-line argument. I just took a look at the MPI-2.2
document and they have a simple example demonstrating how these functions
can to be used. They recommend using gets()/fgets() at the client process to
grab the port information that the user types in, instead of using a
command-line argument. I just tried out a simple/client server application
in this manner and it seems to work fine.
            Regarding the MPI_Comm_spawn error, it appears as though the
"child" executable is not available. Could you possibly try setting the PATH
variable appropriately and try it again?
            Please let us know if you encounter any further problems.

Thanks,
Krishna

On Tue, Apr 13, 2010 at 3:00 PM, Bryan Green <bryan.d.green at nasa.gov> wrote:

> Hello,
>
> I have some questions about using the dynamic process management features
> of
> mvapich 1.4.1.  I'm new to this topic and have not been able to find very
> much specific information on the topic online.
>
> My tests of the MPI_Comm_connect/accept mechanism have not worked and I'm
> wondering what I am missing.
>
> I have a simple server which does the basic setup:
>
>    MPI_Comm client;
>    char port_name[MPI_MAX_PORT_NAME];
>    MPI_Open_port(MPI_INFO_NULL, port_name);
>    printf("server available at %s\n",port_name);
>    MPI_Comm_accept( port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD,  &client
> );
>    ...
>
> and a simple client:
>    MPI_Comm server;
>    char port_name[MPI_MAX_PORT_NAME];
>
>    MPI_Init( &argc, &argv );
>    strcpy(port_name, argv[1] );/* assume server's name is cmd-line arg */
>
>    MPI_Comm_connect( port_name, MPI_INFO_NULL, 0, MPI_COMM_WORLD,
>                      &server );
>
> I run the server:
> $ mpirun_rsh -np 1 n000 MV2_SUPPORT_DPM=1 ./serv
> server available at
> tag#0$description#"#RANK:00000000(00000035:0074004b:00000001)#"$
>
> And I run the client and it fails:
>
> $ mpirun_rsh -np 1 n000 MV2_SUPPORT_DPM=1 ./cli
> 'tag#0$description#"#RANK:00000000(00000035:0074004b:00000001)#"$'
> Fatal error in MPI_Comm_connect:
> Other MPI error, error stack:
> MPI_Comm_connect(119)............................:
> MPI_Comm_connect(port="tag#0##RANK:00000000(00000035:0074004b:00000001)#$",
> MPI_INFO_NULL, root=0, MPI_COMM_WORLD, newcomm=0x7fff720186c8) failed
> MPID_Comm_connect(187)...........................:
> MPIDI_Comm_connect(388)..........................:
> MPIDI_Create_inter_root_communicator_connect(149):
> MPIDI_CH3_Connect_to_root(354)...................: Missing hostname or
> invalid host/port description in business card
> MPI process (rank: 0) terminated unexpectedly on n000
> Exit code -5 signaled from n000
>
>
> Can someone inform me of what I am doing wrong?  Is there documentation on
> using these features with mvapich that I missed?
>
> I have also been testing spawning, but my simple test fails  with the
> message:
> execl failed
> : No such file or directory
>
> It fails inside this call to MPI_Comm_spawn:
> MPI_Comm_spawn("./child", MPI_ARGV_NULL, numToSpawn,
>                   MPI_INFO_NULL, 0, parentComm, &interComm, errCodes);
>
> I'm probably missing something obvious.  I appreciate any help I can get.
>
> Thanks,
> -bryan
>
>
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