Lesson 1 Introducing Jobs

Introduction

Lesson 1 presents the following information about jobs and batch processing:

Until now your logon time in this course has been in session mode. In session mode, the computer acts on a single command at a time. However, in job mode or batch processing, you use the STREAM command to submit an entire series of commands as a "batch" or "job" file to the computer.

   STREAM MYJOB

MYJOB is a job file containing a "batch" of commands. The computer processes these commands without additional input from you. Your results generally are sent to a printer.

	NOTE: MYJOB and some other job files are ready for you to use with this module. Your system manager put them there for your use. Other job files on your system are incomplete. You will have a chance to complete and run them as part of your study.

Advantages of job/batch processing

There are a number of advantages to job processing.

It's much more efficient than session processing. Jobs generally do not require continuous input or your supervision. You can process a number of job commands with a single command. While your job is processing, your terminal is free for other work.

One other advantage of job processing is that the processing can be scheduled to occur at a specific time. A job that requires a large portion of the system's resources may be run at a time when the system is not busy with interactive sessions or other jobs.

Comparison to sessions

How well can you distinguish between jobs and sessions? Label each item below to show which refer to jobs and which refer to sessions.

More SHOWJOB information

You already know that the SHOWJOB command lists all jobs and sessions currently on your system and provides you with the limits for each; however, as you begin working with jobs, you will be interested in the additional information displayed by SHOWJOB.

The following is an example of a SHOWJOB display:

   JOBNUM    STATE  IPRI   JIN    JLIST  INTRODUCED    JOB NAME



   #S201     EXEC          20      20    MON 7:05A     CONSOLE.SYS

   #J30      WAIT   D6     10S     LP    MON 6:30A     JON.FINANCE

   #S230     EXEC          55      55    MON 12:02P    USER2.CLASS

   #J35      INTRO  8      10S     LP    MON 5:45A     STATS.PROJECT

   #J32      EXEC          10S     LP    MON 4:30A     MARY.PROD



   4 JOBS:



      1 INTRO

      1 WAIT

      3 EXEC; INCL 2 SESSIONS

      0 SUSP

      JOBFENCE=6; JLIMIT=11; SLIMIT=20



   CURRENT:  7/20/89  17:30



   JOBNUM    STATE  IPRI   JIN    JLIST  SCHEDULED-INTRO  JOB NAME



   #J33      SCHED  9      10S    LP     7/20/89   20:00  MARY.PROJA

   #J34      SCHED  8      10S    LP     7/20/89   22:00  USER2.CLASS



   2 SCHEDULED JOB(S)

The important terms in the display are described below:

The five possibilities for jobs are:

	NOTE: Questions 2 through 12 refer to the SHOWJOB display.

JOBFENCE, JLIMIT, SLIMIT information

The values for each of these are set by system management and may be adjusted by them to meet the needs of system users.

IPRI (input priority)

This column displays a job's input priority only if that job is in the WAIT or INTRO state, or has been scheduled to run at a later time. D6 means the job has an input priority of 6, but is deferred for later execution. If a job is currently executing or suspended, the job's priority value is not displayed. You might see QUIET in this column. The QUIET means that the user has instructed the system not to interrupt with messages from other users. (The console operator can still interrupt a Quiet session with a WARN command message.)

Input priority values range from 1 (low priority) to 13 (high priority). If you enter HIPRI in the !JOB command line, the priority will be set to 15, but only if you have SM or OP capability; otherwise, the job will be submitted with the highest possible priority available at the time.

Jobs in the EXEC or SUSPEND state do not have IRPR values.

In order for a job to begin executing, the input priority value, IPRI, must be greater than the current jobfence. Once the job has entered the EXEC state, INPRI and the jobfence value have no further meaning for the job.

JIN and JLIST columns

These two columns show the device (LDEV) numbers assigned to input (JIN) devices and output (JLIST) devices. Since sessions are generally input and output from a terminal, these numbers are identical for sessions.

Because jobs are usually input from disk, and output is printed on the line printer (LP), the JIN and JLIST designators for jobs are different.

INTRODUCED and JOBNAME columns

The INTRODUCED column shows the date and time the session or job was started. For a job in the WAIT state, the date and time show when the job was introduced with the STREAM command. As soon as the job enters the EXEC state, the date and time show when the job entered the EXEC state.

The JOBNAME column shows the user and account where the job originated, preceded by the job name, if any.

If a job is scheduled for later submission, its state will be SCHED. It will appear at the end of the SHOWJOB listing. Under the column SCHEDULED-INTRO will be the date and time when the job is scheduled for submission.

Job and session summary

Just beneath the column information is a summary of information regarding jobs and sessions currently executing or awaiting execution on the system. The following information on the jobfence, job limit, and session limit is a list of scheduled jobs with the times they are scheduled to run.

SHOWJOB parameters

Suppose that you want information about just one job.

   SHOWJOB Jobnumber

Or perhaps you want to display only job processing information rather than job and session information to your screen.

   SHOWJOB JOB=@J

The SHOWJOB command has a number of parameters that allow you to specify the kind of information to be displayed.