Controlled premature termination of mpi program running under slurm? - mpi

Question

I am running a script that does multiple subsequent mpirun calls through slurms squeue command. Each call to mpirun will write its output to an own directory, but there is a dependency between them in the way that a given run will use data from the former runs output directory.
The mpi program internally performs some iterative optimization algorithm, which will terminate if some convergence criteria are met. Every once in a while it happens, that the algorithm reaches a state in which those criteria are not quite met yet, but by plotting the output (which is continuosly written to disk) one can quite easily tell that the important things have converged and that further iterations would not change the nature of the final result anymore.
What I am therefore looking for is a way to manually terminate the run in a controlled way and have the outer script proceed to the next mpirun call. What is the best way to achieve this? I do not have direct access to the node on which the calculation is actually performed, but I have of course access to all of slurms commands and the working directories of the individual runs. I have access to the mpi programs full source code.
One solution that would work is the following: If one manually wants to terminate a run, one places a file with a special name like killme in the working directory, which could easily be done with touch killme. The mpi program would regulary check for the existence of this file and terminate in a controlled manner if it exists. The outer script or slurm would not be involved at all here and the script would just continue with the next mpirun call. What do you think of this solution? Can you think of anything better?

Answer 1

Here is a short code snippet for getting SIGUSR1 as a signal.
More detailed explanation can be found here.
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
void sighandler(int signum, siginfo_t *info, void *ptr) {
fprintf(stderr, "Received signal %d\n", signum);
fprintf(stderr, "Signal originates from process %lu\n",
(unsigned long) info->si_pid);
fprintf(stderr, "Shutting down properly.\n");
exit(0);
}
int main(int argc, char** argv) {
struct sigaction act;
printf("pid %lu\n", (unsigned long) getpid());
memset(&act, 0, sizeof(act));
act.sa_sigaction = sighandler;
act.sa_flags = SA_SIGINFO;
sigaction(SIGUSR1, &act, NULL);
while (1) {
};
return 0;
}