[mpich-discuss] mpiexec hydra : signal handling SIGINT with popen

[Roy, Hirak]

Hi All,

I am using a wrapper program which runs "mpiexec -n 5 actual_program" using a popen command.
[ This is the simplified version of running my program. Ideally there is a TCL layer which does these things].
I have attached my program here.

My actual program has installed SIGINT signal handler and takes some action before it exits.
It also writes lot of information on stdout and a file.

In general, if I press CTRL+C, I expect SIGINT to be passed to all the underlying processes.
However, in my case, although the processes receive SIGINT, they are killed immediately.

I have noticed that If I run using
system("mpiexec -n 5 actual_program"),  SIGINT is delivered and appropriate actions are taken.

I am a bit confused here. The only thing I can relate is that there is somehow a SIGPIPE signal which might lead mpiexec to kill all subprocesses.
Can someone please have a look and let me know what is the issue here and what can be a done.

Thanks,
Hirak

// wrapper program

#include <stdio.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>



int main ()
{

  const char* command = "mpiexec -n 5  ./mpiprog.out";
  #if 1
  FILE *fp = popen(command, "r");
  if (!fp) {
    printf ("failed\n");
  }
  while (!feof(fp)) {
    char ch ;
    fscanf(fp, "%c", &ch);
    printf ("%c", ch);
  }

  pclose(fp);
#else
  system (command);
#endif
}

//mpiprog.c
#include "mpi.h"
#include <signal.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

void signalHandler(int signum, siginfo_t *info, void *ptr)
{
  fprintf (stdout,"******** SIGINT *******************\n");
  MPI_Finalize();
  exit (0);
}

int main(int argc, char** argv)
{
  struct sigaction act;
  memset(&act, 0, sizeof(act));
  act.sa_sigaction = signalHandler;
  act.sa_flags = SA_SIGINFO;
  sigaction(SIGINT, &act, NULL);


  MPI_Init(&argc, &argv);


  while (1)
  {

    sleep (10);
    printf ("---Hhahaha\n");
  }

  MPI_Finalize();
}


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