What version of OMPI are you using?
> On Jan 31, 2017, at 7:33 AM, elistrato...@info.sgu.ru wrote:
>
> Hi,
>
> I am trying to write trivial master-slave program. Master simply creates
> slaves, sends them a string, they print it out and exit. Everything works
> just fine, however, when I add a delay (more than 2 sec) before calling
> MPI_Init on slave, MPI fails with MPI_ERR_SPAWN. I am pretty sure that
> MPI_Comm_spawn has some kind of timeout on waiting for slaves to call
> MPI_Init, and if they fail to respond in time, it returns an error.
>
> I believe there is a way to change this behaviour, but I wasn't able to
> find any suggestions/ideas in the internet.
> I would appreciate if someone could help with this.
>
> ---
> --- terminal command i use to run program:
> mpirun -n 1 hello 2 2 // the first argument to "hello" is number of
> slaves, the second is delay in seconds
>
> --- Error message I get when delay is >=2 sec:
> [host:2231] *** An error occurred in MPI_Comm_spawn
> [host:2231] *** reported by process [3453419521,0]
> [host:2231] *** on communicator MPI_COMM_SELF
> [host:2231] *** MPI_ERR_SPAWN: could not spawn processes
> [host:2231] *** MPI_ERRORS_ARE_FATAL (processes in this communicator will
> now abort,
> [host:2231] *** and potentially your MPI job)
>
> --- The program itself:
> #include "stdlib.h"
> #include "stdio.h"
> #include "mpi.h"
> #include "unistd.h"
>
> MPI_Comm slave_comm;
> MPI_Comm new_world;
> #define MESSAGE_SIZE 40
>
> void slave() {
> printf("Slave initialized; ");
> MPI_Comm_get_parent(&slave_comm);
> MPI_Intercomm_merge(slave_comm, 1, &new_world);
>
> int slave_rank;
> MPI_Comm_rank(new_world, &slave_rank);
>
> char message[MESSAGE_SIZE];
> MPI_Bcast(message, MESSAGE_SIZE, MPI_CHAR, 0, new_world);
>
> printf("Slave %d received message from master: %s\n", slave_rank,
> message);
> }
>
> void master(int slave_count, char* executable, char* delay) {
> char* slave_argv[] = { delay, NULL };
> MPI_Comm_spawn( executable,
> slave_argv,
> slave_count,
> MPI_INFO_NULL,
> 0,
> MPI_COMM_SELF,
> &slave_comm,
> MPI_ERRCODES_IGNORE);
> MPI_Intercomm_merge(slave_comm, 0, &new_world);
> char* helloWorld = "Hello New World!\0";
> MPI_Bcast(helloWorld, MESSAGE_SIZE, MPI_CHAR, 0, new_world);
> printf("Processes spawned!\n");
> }
>
> int main(int argc, char* argv[]) {
> if (argc > 2) {
> MPI_Init(&argc, &argv);
> master(atoi(argv[1]), argv[0], argv[2]);
> } else {
> sleep(atoi(argv[1])); /// delay
> MPI_Init(&argc, &argv);
> slave();
> }
> MPI_Comm_free(&new_world);
> MPI_Comm_free(&slave_comm);
> MPI_Finalize();
> }
>
>
> Thank you,
>
> Andrew Elistratov
>
>
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