18
Thu, Apr
5 New Articles
  1. You are here:  
  2. Home
  3. Programming
  4. Programming - Other
  5. Java
  6. TechTip: WRKJVMJOB: Who's Been Running Java in My Shop?

TechTip: WRKJVMJOB: Who's Been Running Java in My Shop?

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

More and more Java is running under the covers on IBM i shops, and this command helps you see where.

 

Even as more and more shops embrace Java, they find that Java doesn't quite fit into the work management framework we've become familiar with on the IBM midrange platform. Specifically, WRKACTJOB just doesn't work the way we need it to. But as of version 6.1, we now have a new tool, WRKJVMJOB.

Java Is a Little Different

If you try to look at a Java job using the traditional WRKACTJOB tools, you won't see much. If you submit a job that calls Java (for example, by using the RUNJVA command), its job log will end with the call to the RUNJVA command and its call stack will be sitting on a call to the program QP0LLIB1, which is a service program that waits on a socket.

 

Socket? What's that all about? Well, what happened is that your program doesn't actually run the Java code. Instead, your job submits another job that actually runs the Java code. If you execute WRKUSRJOB, you can probably find it; the job will be of type BATCHI, and the function will begin with the characters JVM.

 

But even if you find the job, traditional i5/OS work management won't give you a lot of information. The job log will have a few messages about starting the JVM, and that's typically about it. The call stack will be similarly cryptic, with calls to PASE programs and lots of UNIX-y stuff like .so files.

Enter WRKJVMJOB

So, in V6.1, IBM introduced a set of tools that makes it easier for Java developers to monitor Java jobs. Foremost among these is the WRKJVMJOB command. Just hit WRKJVMJOB, and you'll see a list of all the JVM jobs running on your machine:

                               Work with JVM Jobs                      MYI 

                                                             02/05/12  11:42:24

 Active JVMs on system:   5                                                    

                                                                                

 Type options, press Enter.                                                    

   5=Work with   7=Display job log   8=Work with spooled files                 

   9=Display GC information          11=Display threads   12=Dump   13=Print   

 Opt  Job Name    User        Number  Function          Status                 

  _   QSRVMON     QSYS        343115  JVM-ServiceMon     THDW                  

  _   QYPSJSVR    QYPSJSVR    343148  PGM-jvmStartPa     SIGW                  

  _   QJVACMDSRV  JOHNDOE     424242  JVM-MyJavaCls      THDW                  

  _   SERVER1     QEJBSVR     425212  PGM-jvmStartPa     THDW                  

  _   SERVER2     QEJBSVR     425341  PGM-jvmStartPa     THDW                  

                                                                                

                                                                         Bottom

 Parameters or command                                                         

 ===>__________________________________________________________________________

 F3=Exit   F4=Prompt   F5=Refresh    F6=Print     F9=Retrieve                  

 F11=Display subsystem information   F12=Cancel   F16=Resequence               

 

Among the first things you might notice are the system jobs. For instance, QSRVMON is a service monitor job that keeps an eye on the rest of the system, and QYPSJSVR is the support server for Management Central. IBM uses a lot of Java. Next on the list, you see a job running QJVACMDSRV; that's an example of a user job running Java. User JOHNDOE has executed the RUNJVA command, and this is the job that was submitted under the covers. Finally, you'll see a couple of server jobs. They're running under the QEJBSVR user profile, which means they're probably WebSphere server jobs. If you select one of these jobs with option 5, you'll get the Work With Java Virtual Machine display, which has a lot of Java-specific options.

 

                         Work with Java Virtual Machine                        

                                                             System:   MYI

   Job  . . . . . . :   QSRVMON             PID  . . . . . . :   11            

   User . . . . . . :   QSYS                JDK  . . . . . . :   1.6.0         

   Number . . . . . :   343115              Bits . . . . . . :   32            

                                                                               

 Select One of the following:                                                  

                                                                                

      1. Display JVM arguments                                                 

      2. Display environment variables                                         

      3. Display PASE environment variables                                     

      4. Display Java lock information                                         

      5. Display garbage collection information                                

      6. Display initial Java system properties                                 

      7. Display current Java system properties                                

      8. Display Java threads                                                  

      9. Display job log                                                        

     10. Display GC Cycle Table                                                

                                                                               

                                                                        More...

 Selection or command                                                          

 ===> _________________________________________________________________________

 F3=Exit   F4=Prompt   F9=Retrieve   F12=Cancel                                

 

You can see the arguments used to initiate the JVM. Take a look at the environment variables for Java and for PASE and see the system properties, both when the job was first submitted and as they are currently defined. This information is far more useful to a Java developer than what the normal i5/OS tools can provide. Another option on the second page of the menu allows you to generate a Java dump, which sometimes is the only way to diagnose a Java problem.

 

Note that you don't have to go through WRKJVMJOB to get to this screen. If you happen to see a Java job when you're running WRKACTJOB, just select option 5 to run WRKJOB, and then from that menu, select the new option 45 to bring up the Work with Java Virtual Machine display above.

So Hello to the New Tools

Java is a different development environment and, as such, it needs new tools. Hopefully, the WRKJVMJOB command will be one of those tools that makes your Java development job a little easier.

 

 

Joe Pluta

Joe Pluta is the founder and chief architect of Pluta Brothers Design, Inc. He has been extending the IBM midrange since the days of the IBM System/3. Joe uses WebSphere extensively, especially as the base for PSC/400, the only product that can move your legacy systems to the Web using simple green-screen commands. He has written several books, including Developing Web 2.0 Applications with EGL for IBM i, E-Deployment: The Fastest Path to the Web, Eclipse: Step by Step, and WDSC: Step by Step. Joe performs onsite mentoring and speaks at user groups around the country. You can reach him at This email address is being protected from spambots. You need JavaScript enabled to view it..

MC Press books written by Joe Pluta available now on the MC Press Bookstore.

Developing Web 2.0 Applications with EGL for IBM i Developing Web 2.0 Applications with EGL for IBM i
Joe Pluta introduces you to EGL Rich UI and IBM’s Rational Developer for the IBM i platform.
List Price $39.95

Now On Sale

WDSC: Step by Step WDSC: Step by Step
Discover incredibly powerful WDSC with this easy-to-understand yet thorough introduction.
List Price $74.95

Now On Sale
Eclipse: Step by Step Eclipse: Step by Step
Quickly get up to speed and productivity using Eclipse.
List Price $59.00

Now On Sale
BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$0.00 Raised:
$

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: