29
Fri, Nov
0 New Articles

Debugging Batch Jobs

General
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Have you ever changed a batch program to run interactively just so you could use the debug feature on it? Have you ever pondered buying a third-party debug tool just to find those errors that inevitably show up on job logs? Have you ever stared at a program until your eyes glazed over trying to find the intermittent mystery error that keeps popping up when the third-shift operator runs the nightly batch run? If you an-swered yes to any of these questions, you should read this article.

The system debugger that comes with your AS/400 may not have all the features of some of the third-party debuggers, but it has one great advantage the others cannot claim to have-it's free.

Most AS/400 programmers know the basics of starting debug, setting breakpoints, and displaying and changing program variables. Let's skip the fundamentals and focus instead on debugging batch programs. Debugging batch jobs is not very different from the debugging you're already familiar with.

Starting the Service Job

To run debug on a batch program, you need to use a feature called a service job. Before initiating the service job, you need three components: the job name, the user, and the job number.

Finding the information is easy if the program happens to be at an error message or is already running (does the term looping sound familiar?). You can use the Work with Active Jobs (WRKACTJOB) or Work with Submitted Jobs (WRKSBMJOB) command to find the job in question. When you select the Work with Job option, you will find the three parameters you need displayed at the top of the screen as shown in 1.

Finding the information is easy if the program happens to be at an error message or is already running (does the term looping sound familiar?). You can use the Work with Active Jobs (WRKACTJOB) or Work with Submitted Jobs (WRKSBMJOB) command to find the job in question. When you select the Work with Job option, you will find the three parameters you need displayed at the top of the screen as shown in Figure 1.

If the job is already running, you need to put the job on hold using the WRKACTJOB or WRKSBMJOB panel.

On the other hand, if the job you want to debug is not already running, you need to go about it a little differently. You do not want the job to begin running until you have initiated the service job. Place the job queue on hold using the Hold Job Queue (HLDJOBQ) command and then submit the job. Placing the job queue on hold does not stop existing programs from running, but it does keep new jobs in the queue from being initiated. Use the WRKSBMJOB command to get the job identification parameters, so you can start the service job.

By now, you should have written down the job name, user, and job number. You can run the Start Service Job (STRSRVJOB) command from any workstation. If you use F4 your screen will look like 2.

By now, you should have written down the job name, user, and job number. You can run the Start Service Job (STRSRVJOB) command from any workstation. If you use F4 your screen will look like Figure 2.

Starting Debug

Now that you have started the service job, you need to put the program into debug mode. You can use the Start Debug (STRDBG) command just as if you were putting an interactive program into debug mode. However, the system won't let you add your breakpoints until the job begins.

Now it's time to release the job queue using the Release Job Queue (RLSJOBQ) command. If the job is already running, use the Release Job (RLSJOB) command. If the job has not yet started, a screen will be displayed letting you know that the serviced job is about to begin. You can expect a screen that looks something like 3.

Now it's time to release the job queue using the Release Job Queue (RLSJOBQ) command. If the job is already running, use the Release Job (RLSJOB) command. If the job has not yet started, a screen will be displayed letting you know that the serviced job is about to begin. You can expect a screen that looks something like Figure 3.

Defining Your Breakpoints

At this point, you must press F10 to get a command entry screen. You have put your program into debug, but you have not told the system where you want it to break. Use the Add Breakpoint (ADDBKP) or Add Trace (ADDTRC) command to define where you want your program to stop, just like you would if you were debugging an interactive job.

Perform the rest of the debug functions as if the program were running in an interactive job. That is all there is to it! When the job completes, you receive another break message that tells you the job being serviced has ended. (Do not confuse this with ending the service job.)

Word of Caution

You will need to end both debug and the service job, or you may encounter problems later. Use the End Debug (ENDDBG) command followed by the End Service Job (ENDSRVJOB) command.

In Summary

Although it is a little clunky, debug on the AS/400 can be an extremely useful tool if you take the time to learn it. The CL Programmer's Guide contains a useful chapter called "Testing Functions" that provides additional insights into debugging both interactive and batch jobs.

Doug Pence and Ron Hawkins have worked on IBM midrange systems for many years. Doug is the founder and Ron is the research and development manager of Computer Processing Unlimited, Inc. in San Diego, California.

REFERENCE AS/400 CL Programmer's Guide (SC21-8077-2, CD-ROM QBKA7102).


Debugging Batch Jobs

Figure 1 The Work with Job Panel

 Work with Job System: CPU Job: ATBRPT User: QPGMR Number: 541492 Select one of the following: 1. Display job status attributes 2. Display job definition attributes 3. Display job run attributes, if active 4. Work with spooled files 10. Display job log, if active or on job queue 11. Display call stack, if active 12. Work with locks, if active 13. Display library list, if active 14. Display open files, if active 15. Display file overrides, if active 16. Display commitment control status, if active More... Selection or command ===> F3=Exit F4=Prompt F9=Retrieve F12=Cancel 
Debugging Batch Jobs

Figure 2 Start Service Job Prompt

 Start Service Job (STRSRVJOB) Type choices, press Enter. Job name . . . . . . . . . . . . JOB atbrpt User . . . . . . . . . . . . . qpgmr Number . . . . . . . . . . . . 541492 Bottom F3=Exit F4=Prompt F5=Refresh F10=Additional parameters F12=Cancel F13=How to use this display F24=More keys 
Debugging Batch Jobs

Figure 3 The Released Serviced Job Screen

 Start Serviced Job System: CPU Job: ATBRPT User: QPGMR Number: 541492 The serviced job has been released from the job queue. Press Enter to start the job or F10 to enter debug commands for that job. Press Enter to continue. F10=Command entry (C) COPYRIGHT IBM CORP. 1980, 1993. 
BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: