This section describes the notes on monitoring J2EE applications by using Java VisualVM

• Operations of Java VisualVM can be guaranteed only in an environment in which a Developer is installed.
• Java VisualVM monitors only those J2EE applications that are running on the same machine on which you are going to perform the operations. You can automatically connect to Java VisualVM when you are connecting to the applications to be monitored.
• Only the user executing the applications to be monitored must execute Java VisualVM. If you execute Java VisualVM as a different user, you cannot monitor the applications.
• While executing Java VisualVM there might be a hang up or delay in response for the Java VisualVM and the applications that are being monitored. In such cases, take either of the following actions:
  
  • Reduce the number of threads running on the applications to be monitored.
  • Use the functionality provided by Cosminexus Developer's Kit for Java described in the following table.
    

    Table K-1 Functionality provided by Cosminexus Developer's Kit for Java

    Item No.	Functionality	Explanation
    1	Extended thread dump functionality and extended VerboseGC functionality	Monitoring the Java heap and Perm heap size
    2	Extended thread dump functionality	Thread information
    3	javagc command	Execution of FullGC

  Do not monitor the applications for which hang-up or response delay has occurred in Java VisualVM.
  
• As the following functionality provided in Java VisualVM does not correspond to the explicit heap management functionality, you cannot check the information of the explicit management heap functionality.
  
  • Memory profiling of the application profiling functionality
  • Memory profiling of application sampling functionality
  • Reference heap dump functionality of the application
  If you want to check the information of the Explicit Memory Management functionality, check the information provided by Cosminexus Developer's Kit for Java such as event log, extended thread dump described in the product JavaVM log file (hereafter called JavaVM).
  
• If the garbage collection occurs in the monitoring functionality of applications in Java VisualVM, the application sampling functionality, and the application profiling functionality, output the extended verbosegc information to the JavaVM log file. In such cases, all types of garbage collection of extended verbosegc information that is output becomes Full GC.
  The following table describes the cause of garbage collection that is output to the extended verbosegc information for each function.
  

  Table K-2 Cause of occurrence of garbage collection of the extended verbosegc information

  Item No.	Java VisualVM functionality with garbage collection	Cause of the occurrence garbage collection of extended verbosegc information
  1	Application monitoring functionality	System.gc
  2	Application sampling functionality	System.gc
  3	Application profiling functionality	JVMTIForceGC

• The fixed value such as Application might be displayed on the Application Window as follows:
  

  Application (pid-numeric value)

  In this case, check whether the PID corresponds to the J2EE server processes by using the task manager. You can check the corresponding PIDs with the Process tab on Windows Task Manager. When you are processing the J2EE server, cjstartsv.exe is displayed in Image name.
  
• When the application to be monitored in Java VisualVM is J2EE server, Unknown is displayed in the Main class of Overview tab on the Main window. The class including the Main method is not displayed. None is displayed in Argument.
• When the application to be monitored in Java VisualVM is J2EE server, and if you are collecting the thread dumps of an application, the following message is output to the sub tab of the Main window and the thread dump is not output.
  

  Writing Java core to full-path-name-of-thread-dump-file...OK

  To check the contents of the thread dump, see the contents of the thread dump file displayed in full-path-name-of-thread-dump-file.
  

However, if the Stop standard output option of the extended thread dump is specified in the startup options of the J2EE server and if the J2EE server is started to output the extended thread dump in standard output format, the thread dump can be output to the Main window tab.