6.3. How to execute back ground job

This indicates how to execute MPI program in back ground.

6.3.1. Back ground execution

This indicates the specification example of back ground execution.

$ mpiexec -n 5 --vcoordfile vcoord_file ./a.out &

Option

Contents

-n

Specify parallel number

--vcoordfile

Specifies that parallel processes be allocated based on the list of coordinates specified in the VCOORD_FILE file.

See also

The description format of the coordinates in the VCOORD_FILE file is conformed to the format of rank-map-hostfile parameter of pjsub command’s --mpi option. For details, refer to the following in the manual “MPI User’s Guide”.

  • --vcoordfile explanation of “Options that can be specified in global_options”

  • “VCOORD file format”

6.3.2. Job creation example

This section shows an example of creating a job script that executes five parallel executions in three backgrounds.
node specification is as 1 dimention.

  1. Create VCOORD_FILE file

    VCOORD_FILE file is created as conforming to rank-map-hostfile parameter format. Create so that the coordinates do not overlap between mpiexec to be executed simultaneously. If there is a duplicate, an error will occur. Here, create as the file name of vcode1, vcode2, vcode3. Indicate file contents in below.

[vcode1]

(0)
(1)
(2)
(3)
(4)

[vcode2]

(5)
(6)
(7)
(8)
(9)

[vcode3]

(10)
(11)
(12)
(13)
(14)

  1. Create a job script

    Create a job script as following.

#!/bin/bash -x
#
#PJM -L "node=15"         # Number of total node required to process of executing at the same time
#PJM -L "rscgrp=small"
#PJM -L "elapse=01:00:00"
#PJM -g groupname
#PJM -x PJM_LLIO_GFSCACHE=/vol000N
#PJM -s
#

mpiexec -n 5 --vcoordfile vcode1 ./sample_mpi &
mpiexec -n 5 --vcoordfile vcode2 ./sample_mpi &
mpiexec -n 5 --vcoordfile vcode3 ./sample_mpi &

wait       # Input the process to wait until finishing back ground job

6.3.3. Notes on back ground execution

  • The maximum number that can be executed simultaneously in background execution is 128.
    If the number exceeds 128, the background job will not be accepted with the message “[ERR.] PLE 0050 plexec cannot be executed any further.”

  • When executing multiple background jobs, it is necessary to specify the VCOORD_FILE file.

  • The VCOORD_FILE file cannot have overlapping coordinates between background jobs running simultaneously. An error will occur if the coordinates are duplicated.

  • If there is no end-waiting by wait, processing of the job script ends regardless of the presence or absence of the background job, and processing of the job also ends.

  • In principle, it cannot be used at the same time as dynamic process generation, but it can be used only when all of the following conditions are satisfied.

    • Multiple mpiexec is not executed at the same time.

    • The number of MPI_COMM_WORLD of the dynamic process that exists simultaneously does not exceed 65535.

    • On 1 execution of mpiexec command, the total number of calls to the MPI_COMM_SPAWN or MPI_COMM_SPAWN_MULTIPLE routine does not exceed 4294967295.