DESCRIPTIONThe design of srun_cr is inspired by mpiexec_cr from MVAPICH2 and cr_restart form BLCR. It is a wrapper around the srun command to enable batch job checkpoint/restart support when used with Slurm's checkpoint/blcr plugin.
The srun_cr execute line options are identical to those of the srun command. See "man srun" for details.
DETAILSAfter initialization, srun_cr registers a thread context callback function. Then it forks a process and executes "cr_run --omit srun" with its arguments. cr_run is employed to exclude the srun process from being dumped upon checkpoint. All catchable signals except SIGCHLD sent to srun_cr will be forwarded to the child srun process. SIGCHLD will be captured to mimic the exit status of srun when it exits. Then srun_cr loops waiting for termination of tasks being launched from srun.
The step launch logic of Slurm is augmented to check if srun is running under srun_cr. If true, the environment variable SLURM_SRUN_CR_SOCKET should be present, the value of which is the address of a Unix domain socket created and listened to be srun_cr. After launching the tasks, srun tries to connect to the socket and sends the job ID, step ID and the nodes allocated to the step to srun_cr.
Upon checkpoint, srun_cr checks to see if the tasks have been launched. If not srun_cr first forwards the checkpoint request to the tasks by calling the Slurm API slurm_checkpoint_tasks() before dumping its process context.
Upon restart, srun_cr checks to see if the tasks have been previously launched and checkpointed. If true, the environment variable SLURM_RESTART_DIR is set to the directory of the checkpoint image files of the tasks. Then srun is forked and executed again. The environment variable will be used by the srun command to restart execution of the tasks from the previous checkpoint.
COPYINGCopyright (C) 2009 National University of Defense Technology, China. Produced at National University of Defense Technology, China (cf, DISCLAIMER).
This file is part of Slurm, a resource management program. For details, see <http://slurm.schedmd.com/>.
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.