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Slurm API


slurm_step_ctx_create, slurm_step_ctx_create_no_alloc, slurm_step_ctx_daemon_per_node_hack, slurm_step_ctx_get, slurm_step_ctx_params_t_init, slurm_jobinfo_ctx_get, slurm_spawn_kill, slurm_step_ctx_destroy − Slurm task spawn functions


#include <slurm/slurm.h>

slurm_step_ctx slurm_step_ctx_create (

slurm_step_ctx_params_t *step_req


slurm_step_ctx slurm_step_ctx_create_no_alloc (

slurm_step_ctx_params_t *step_req


int slurm_step_ctx_daemon_per_node_hack (

slurm_step_ctx_t *ctx


int slurm_step_ctx_get (

slurm_step_ctx_t *ctx,

int ctx_key,



int slurm_jobinfo_ctx_get (

switch_jobinfo_t jobinfo,

int data_type,

void *data


void slurm_step_ctx_params_t_init (

slurm_step_ctx_params_t *step_req


int slurm_spawn {

slurm_step_ctx ctx,

int *fd_array


int slurm_spawn_kill {
slurm_step_ctx ctx,

uint16_t signal


int slurm_step_ctx_destroy {

slurm_step_ctx ctx




Specifies the pointer to the structure with job step request specification. See slurm.h for full details on the data structure’s contents.


Job step context. Created by slurm_step_ctx_create, or slurm_step_ctx_create_no_alloc used in subsequent function calls, and destroyed by slurm_step_ctx_destroy.


Identifies the fields in ctx to be collected by slurm_step_ctx_get.


Storage location for requested data. See data_type below.


Switch−specific data requested. The interpretation of this field depends upon the switch plugin in use.


Array of socket file descriptors to be connected to the initiated tasks. Tasks will be connected to these file descriptors in order of their task id. This socket will carry standard input, output and error for the task. jobinfo Switch−specific job information as returned by slurm_step_ctx_get.


Signal to be sent to the spawned tasks.


slurm_jobinfo_ctx_get Get values from a jobinfo field as returned by slurm_step_ctx_get. The operation of this function is highly dependent upon the switch plugin in use.

slurm_step_ctx_create Create a job step context. To avoid memory leaks call slurm_step_ctx_destroy when the use of this context is finished. NOTE: this function creates a slurm job step. Call slurm_spawn in a timely fashion to avoid having job step credentials time out. If slurm_spawn is not used, explicitly cancel the job step.

slurm_step_ctx_create_no_alloc Same as above, only no allocation is made. To avoid memory leaks call slurm_step_ctx_destroy when the use of this context is finished.

slurm_step_ctx_daemon_per_node_hack Hack the step context to run a single process per node, regardless of the settings selected at slurm_step_ctx_create time.

slurm_step_ctx_get Get values from a job step context. ctx_key identifies the fields to be gathered from the job step context. Subsequent arguments to this function are dependent upon the value of ctx_key. See the CONTEXT KEYS section for details.

slurm_step_ctx_params_t_init This initializes parameters in the structure that you will pass to slurm_step_ctx_create().

slurm_spawn Spawn tasks based upon a job step context and establish communications with the tasks using the socket file descriptors specified. Note that this function can only be called once for each job step context. Establish a new job step context for each set of tasks to be spawned.

slurm_spawn_kill Signal the tasks spawned for this context by slurm_spawn.

slurm_step_ctx_destroy Destroy a job step context created by slurm_step_ctx_create.



Set the argument count and values for the executable. Accepts two additional arguments, the first of type int and the second of type char **.


Have the remote process change directory to the specified location before beginning execution. Accepts one argument of type char * identifying the directory’s pathname. By default the remote process will execute in the same directory pathname from which it is spawned. NOTE: This assumes that same directory pathname exists on the other nodes.


Sets the environment variable count and values for the executable. Accepts two additional arguments, the first of type int and the second of type char **. By default the current environment variables are copied to started task’s environment.


Get the job step response message. Accepts one additional argument of type job_step_create_response_msg_t **.


Get the step id of the created job step. Accepts one additional argument of type uint32_t *.


Get the number of tasks per node for a given job. Accepts one additional argument of type uint32_t **. This argument will be set to point to an array with the task counts of each node in an element of the array. See SLURM_STEP_CTX_TID below to determine the task ID numbers associated with each of those tasks.


Get the task ID numbers associated with the tasks allocated to a specific node. Accepts two additional arguments, the first of type int and the second of type uint32_t **. The first argument identifies the node number of interest (zero origin). The second argument will be set to point to an array with the task ID numbers of each task allocated to the node (also zero origin). See SLURM_STEP_CTX_TASKS above to determine how many tasks are associated with each node.


For slurm_step_ctx_create a context is return upon success. On error NULL is returned and the Slurm error code is set appropriately.

For all other functions zero is returned upon success. On error, −1 is returned, and the Slurm error code is set appropriately.


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_DISABLED the ability to create a job step is currently disabled. This is indicative of the job being suspended. Retry the call as desired.

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.


SEE slurm_step_launch(3) man page for an example of slurm_step_ctx_create and slurm_step_launch in use together.


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) 2004-2007 The Regents of the University of California. 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_allocate_resources(3), slurm_job_step_create(3), slurm_kill_job(3), slurm_get_errno(3), slurm_perror(3), slurm_strerror(3), srun(1)