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Sun Java System Application Server Platform Edition 9.0 Developer's Guide 
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Chapter 4

Debugging Applications

This chapter gives guidelines for debugging applications in the Sun Java System Application Server. It includes the following sections:

Enabling Debugging

When you enable debugging, you enable both local and remote debugging. To start the server in debug mode, use the --debug option as follows:

asadmin start-domain --debug [domain-name]

You can then attach to the server from the debugger at its default JPDA port, which is 9009. For example, for UNIX systems:

jdb -attach 9009

For Windows:

jdb -connect com.sun.jdi.SocketAttach:port=9009

Application Server debugging is based on the JPDA (Java Platform Debugger Architecture). For more information, see JPDA Options.

You can enable debugging even when the application server is started without the --debug option. This is useful if you start the application server from the Windows Start Menu or if you want to make sure that debugging is always turned on.

ProcedureTo set the server to automatically start up in debug mode

Steps
  1. Select the JVM Settings component under the relevant configuration in the Admin Console.

  2. Check the Debug Enabled box.

  3. To specify a different port (from 9009, the default) to use when attaching the JVM to a debugger, specify address= port-number in the Debug Options field.

  4. If you wish to add JPDA options, add any desired JPDA debugging options in Debug Options. See JPDA Options .

See Also

For details, see the Sun Java System Application Server Platform Edition 9.0 Administration Guide.

JPDA Options

The default JPDA options in Application Server are as follows:

-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9009

For Windows, you can change dt_socket to dt_shmem.

If you substitute suspend=y, the JVM starts in suspended mode and stays suspended until a debugger attaches to it. This is helpful if you want to start debugging as soon as the JVM starts.

To specify a different port (from 9009, the default) to use when attaching the JVM to a debugger, specify address=port-number.

You can include additional options. A list of JPDA debugging options is available at http://java.sun.com/products/jpda/doc/conninv.html#Invocation.

Generating a Stack Trace for Debugging

You can generate a Java stack trace for debugging as described here if the Application Server is in verbose mode (see Enabling Verbose Mode):

http://developer.java.sun.com/developer/technicalArticles/Programming/Stacktrace/

The stack trace goes to the domain-dir/logs/server.log file and also appears on the command prompt screen.

If the -Xrs flag is set (for reduced signal usage) in the domain.xml file (under jvm-options), comment it out before generating the stack trace. If the -Xrs flag is used, the server might simply dump core and restart when you send the signal to generate the trace. For more about the domain.xml file, see the Sun Java System Application Server Platform Edition 9.0 Administration Reference.

The Java Debugger

The Java Debugger (jdb) helps you find and fix bugs in Java language programs. When using the jdb debugger with the Application Server, you must attach to the server from the debugger at its default JPDA port, which is 9009. For example, for UNIX systems:

jdb -attach 9009

For Windows:

jdb -connect com.sun.jdi.SocketAttach:port=9009

For more information about the jdb debugger, see the following links:

Java Platform Debugger Architecture - The Java Debugger: http://java.sun.com/products/jpda/doc/soljdb.html

Java Platform Debugger Architecture - Connecting with JDB: http://java.sun.com/products/jpda/doc/conninv.html#JDB

You can attach to the Application Server using any JPDA compliant debugger, including that of NetBeans, Sun Java Studio, JBuilder, Eclipse, and so on.

Using an IDE

You can use an IDE (integrated development environment) with the Application Server to take advantage of the IDE's debugging features.

ProcedureTo use the NetBeans IDE for Debugging

The following steps are applicable to the NetBeans 5 IDE and the Sun Java Studio 8 software, which is built on the NetBeans IDE.

Steps
  1. Download the latest version of NetBeans from http://www.netbeans.org.

    This site also provides documentation for the NetBeans IDE.

  2. Start the NetBeans IDE.

  3. If an Application Server is not already configured in the NetBeans IDE, perform the following steps:

    1. Select the Runtime tab to display the Runtime window.

    2. Right-click on Servers in the Runtime window.

    3. Select the Add Server command from the menu.

    4. On the first screen, select Sun Java System Application Server in the Server field, and type a name in the Name field. Select Next.

    5. On the second screen, fill in the requested configuration information. In the Domains folder field, use the Browse button to go to the Application Server domain-root-dir directory.

    6. Click Finish.

  4. Create a project (an application or module) in the NetBeans IDE.

  5. Right-click on the project in the component tree and select Debug Project from the menu.

    This stops the Application Server and restarts it in debug mode.

  6. Set break points in your source file in the NetBeans IDE as usual, and run the application.

Sun Java System Message Queue Debugging

Sun Java System Message Queue has a broker logger, which can be useful for debugging JMS, including message-driven bean, applications. You can adjust the logger's verbosity, and you can send the logger output to the broker's console using the broker's -tty option. For more information, see the Sun Java System Message Queue 3 2006Q2 Administration Guide.

Enabling Verbose Mode

If you want to see the server logs and messages printed to System.out on your command prompt screen, you can start the server in verbose mode. This makes it easy to do simple debugging using print statements, without having to view the server.log file every time.

When the server is in verbose mode, messages are logged to the console or terminal window in addition to the log file. In addition, pressing Ctrl-C stops the server and pressing Ctrl-\ prints a thread dump. To start the server in verbose mode, use the --verbose option as follows:

asadmin start-domain --verbose [domain-name]

You can enable verbose mode even when the application server is started without the --verbose option. This is useful if you start the application server from the Windows Start Menu or if you want to make sure that verbose mode is always turned on.

You can set the server to automatically start up in verbose mode using the Admin Console. For details, see the Sun Java System Application Server Platform Edition 9.0 Administration Guide.

Logging

You can use the Application Server's log files to help debug your applications. In the Admin Console, select the Application Server component, then click on the Open Log Viewer button in the General Information page. For details about logging, see the Sun Java System Application Server Platform Edition 9.0 Administration Guide.

Profiling

You can use a profiler to perform remote profiling on the Application Server to discover bottlenecks in server-side performance. This section describes how to configure these profilers for use with the Application Server:

Information about comprehensive monitoring and management support in the Java™ 2 Platform, Standard Edition (Java SE™ platform) version 6 is available at http://java.sun.com/j2se/1.5.0/docs/guide/management/index.html.

The HPROF Profiler

HPROF is a simple profiler agent shipped with the Java 2 SDK. It is a dynamically linked library that interacts with the JVMPI and writes out profiling information either to a file or to a socket in ASCII or binary format.

HPROF can present CPU usage, heap allocation statistics, and monitor contention profiles. In addition, it can also report complete heap dumps and states of all the monitors and threads in the Java virtual machine. For more details on the HPROF profiler, see the JDK documentation at http://java.sun.com/j2se/1.4.2/docs/guide/jvmpi/jvmpi.html#hprof.

Once HPROF is enabled using the following instructions, its libraries are loaded into the server process.

ProcedureTo use HPROF profiling on UNIX

Steps
  1. Configure the Application Server using the Admin Console:

    1. Select the JVM Settings component under the relevant configuration, then select the Profiler tab.

    2. Edit the following fields:

      • Profiler Name: hprof

      • Profiler Enabled: true

      • Classpath: (leave blank)

      • Native Library Path: (leave blank)

      • JVM Option: For each of these options, select Add, type the option in the Value field, then check its box:

        -Xrunhprof:file=log.txt,options

        Here is an example of options you can use:

        -Xrunhprof:file=log.txt,thread=y,depth=3

        The file option determines where the stack dump is written in Step 2.

        The syntax of HPROF options is as follows:

        -Xrunhprof[:help]|[:option=value,option2=value2, ...]

        Using help lists options that can be passed to HPROF. The output is as follows:

        Hprof usage: -Xrunhprof[:help]|[:<option>=<value>, ...]

        Option Name and Value Description Default
        --------------------- ----------- -------
        heap=dump|sites|all heap profiling all
        cpu=samples|old CPU usage off
        format=a|b ascii or binary output a
        file=<file> write data to file java.hprof
        (.txt for ascii)
        net=<host>:<port> send data over a socket write to file
        depth=<size> stack trace depth 4
        cutoff=<value> output cutoff point 0.0001
        lineno=y|n line number in traces? y
        thread=y|n thread in traces? n
        doe=y|n dump on exit? y

  2. Restart the Application Server. This writes an HPROF stack dump to the file you specified using the file HPROF option in Step 1.

The Optimizeit Profiler

You can purchase Optimizeit™ from Borland at http://www.borland.com/optimizeit.

Once Optimizeit is enabled using the following instructions, its libraries are loaded into the server process.

ProcedureTo enable remote profiling with Optimizeit

Steps
  1. Configure your operating system:

  2. Configure the Application Server using the Admin Console:

    1. Select the JVM Settings component under the relevant configuration, then select the Profiler tab.

    2. Edit the following fields:

      • Profiler Name: optimizeit

      • Profiler Enabled: true

      • Classpath: Optimizeit-dir/lib/optit.jar

      • Native Library Path: Optimizeit-dir/lib

      • JVM Option: For each of these options, select Add, type the option in the Value field, then check its box:

        -DOPTITHOME=Optimizeit-dir  -Xrunpri:startAudit=t 
        -Xbootclasspath/p:/Optimizeit-dir/lib/oibcp.jar

  3. In addition, you might have to set the following in your server.policy file.

    For more information about the server.policy file, see The server.policy File

    grant codeBase "file:Optimizeit-dir/lib/optit.jar" {
    permission java.security.AllPermission;
    };

  4. Restart the Application Server.

    When the server starts up with this configuration, you can attach the profiler.

See Also

For further details, see the Optimizeit documentation.

Troubleshooting

If any of the configuration options are missing or incorrect, the profiler might experience problems that affect the performance of the Application Server.


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