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Man Pages

Manual Reference Pages  -  SLURM_STEP_LAUNCH (3)


slurm_step_launch_params_t_init, slurm_step_launch, slurm_step_launch_fwd_signal, slurm_step_launch_wait_start, slurm_step_launch_wait_finish, slurm_step_launch_abort - Slurm job step launch functions



#include <slurm/slurm.h>

void slurm_step_launch_params_t_init (
        slurm_step_launch_params_t *launch_req

int slurm_step_launch (
        slurm_step_ctx ctx,
        const slurm_step_launch_params_t *launch_req,
        const slurm_step_launch_callbacks_t callbacks

void slurm_step_launch_fwd_signal (
        slurm_step_ctx ctx,
        int signo

int slurm_step_launch_wait_start (
        slurm_step_ctx ctx

void slurm_step_launch_wait_finish (
        slurm_step_ctx ctx

void slurm_step_launch_abort {
        slurm_step_ctx ctx


  Identify functions to be called when various events occur.
ctx Job step context. Created by slurm_step_ctx_create, used in subsequent function calls, and destroyed by slurm_step_ctx_destroy.
  Pointer to a structure allocated by the user containing specifications of the job step to be launched.


slurm_step_launch_params_t_init initialize a user-allocated slurm_step_launch_params_t structure with default values. default values. This function will NOT allocate any new memory.

slurm_step_launch Launch a parallel job step.

slurm_step_launch_fwd_signal Forward a signal to all those nodes with running tasks.

slurm_step_launch_wait_start Block until all tasks have started.

slurm_step_launch_wait_finish Block until all tasks have finished (or failed to start altogether).

slurm_step_launch_abort Abort an in-progress launch, or terminate the fully launched job step. Can be called from a signal handler.

IO Redirection

Use the local_fds entry in slurm_step_launch_params_t to specify file descriptors to be used for standard input, output and error. Any local_fds not specified will result in the launched tasks using the calling process’s standard input, output and error. Threads created by slurm_step_launch will completely handle copying data between the remote processes and the specified local file descriptors.

Use the substructure in slurm_step_io_fds_t to restrict the redirection of I/O to a specific node or task ID. For example, to redirect standard output only from task 0, set


Use the remote_*_filename fields in slurm_step_launch_params_t to have launched tasks read and/or write directly to local files rather than transferring data over the network to the calling process. These strings support many of the same format options as the srun command. Any remote_*_filename fields set will supersede the corresponding local_fds entries. For example, the following code will direct each task to write standard output and standard error to local files with names containing the task ID (e.g. "/home/bob/test_output/run1.out.0" and "/home/bob/test_output/run.1.err.0" for task 0).

params.remote_output_filename = "/home/bob/test_output/run1.out.%t"
params.remote_error_filename  = "/home/bob/test_output/run1.err.%t"


slurm_step_launch and slurm_step_launch_wait_start will return SLURM_SUCCESS when all tasks have successfully started, or SLURM_ERROR if the job step is aborted during launch.


EINVAL Invalid argument

SLURM_PROTOCOL_VERSION_ERROR Protocol version has changed, re-link your code.

ESLURM_INVALID_JOB_ID the requested job id does not exist.

ESLURM_ALREADY_DONE the specified job has already completed and can not be modified.

ESLURM_ACCESS_DENIED the requesting user lacks authorization for the requested action (e.g. trying to delete or modify another user’s job).

ESLURM_INTERCONNECT_FAILURE failed to configure the node interconnect.

ESLURM_BAD_DIST task distribution specification is invalid.

SLURM_PROTOCOL_SOCKET_IMPL_TIMEOUT Timeout in communicating with Slurm controller.


 * To compile:
 * gcc test.c -o test -g -pthread -lslurm
 * Or if Slurm is not in your default search paths:
 * gcc test.c -o test -g -pthread -I{$SLURM_DIR}/include \
 *     -Wl,--rpath={$SLURM_DIR}/lib -L{$SLURM_DIR}/lib -lslurm
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <slurm/slurm.h>
#include <slurm/slurm_errno.h>

static void _task_start(launch_tasks_response_msg_t *msg) {         printf("%d tasks started on node %s\n",                 msg->count_of_pids, msg->node_name); }

static void _task_finish(task_exit_msg_t *msg) {         printf("%d tasks finished\n", msg->num_tasks); }

int main (int argc, char *argv[]) {         slurm_step_ctx_params_t step_params;         slurm_step_ctx step_ctx;         slurm_step_launch_params_t params;         slurm_step_launch_callbacks_t callbacks;         uint32_t job_id, step_id;

        slurm_step_ctx_params_t_init(&step_params);         step_params.node_count = 1;         step_params.task_count = 4;         step_params.overcommit = true;

        step_ctx = slurm_step_ctx_create(&step_params);         if (step_ctx == NULL) {                 slurm_perror("slurm_step_ctx_create");                 exit(1);         }         slurm_step_ctx_get(step_ctx, SLURM_STEP_CTX_JOBID, &job_id);         slurm_step_ctx_get(step_ctx, SLURM_STEP_CTX_STEPID, &step_id);         printf("Ready to start job %u step %u\n", job_id, step_id);

        slurm_step_launch_params_t_init(¶ms);         params.argc = argc - 1;         params.argv = argv + 1;         callbacks.task_start = _task_start;         callbacks.task_finish = _task_finish;         if (slurm_step_launch(step_ctx, NULL, ¶ms, &callbacks)                         != SLURM_SUCCESS) {                 slurm_perror("slurm_step_launch");                 exit(1);         }         printf("Sent step launch RPC\n");

        if (slurm_step_launch_wait_start(step_ctx) != SLURM_SUCCESS) {                 fprintf(stderr, "job step was aborted during launch\n");         } else {                 printf("All tasks have started\n");         }

        slurm_step_launch_wait_finish(step_ctx);         printf("All tasks have finished\n");

        slurm_step_ctx_destroy(step_ctx);         exit(0); }


These functions are included in the libslurm library, which must be linked to your process for use (e.g. "cc -lslurm myprog.c").


Copyright (C) 2006-2007 The Regents of the University of California. Copyright (C) 2008 Lawrence Livermore National Security. Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). CODE-OCEC-09-009. All rights reserved.

This file is part of Slurm a resource management program. For details, see <>.

Slurm is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Slurm is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.


slurm_step_ctx_create(3), slurm_step_ctx_destroy(3), slurm_get_errno(3), slurm_perror(3), slurm_strerror(3), salloc(1), srun(1)

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April 2015 SLURM API (3) Slurm job step launch functions

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