Java Health Center- a low overhead monitoring tool

Also see: Extracting data from Java Health Center

Java™ Health Center:


Health Center is a very low overhead monitoring tool. It runs alongside an IBM Java application with a very small impact on the application's performance. Health Center monitors several application areas, using the information to provide recommendations and analysis that help you improve the performance and efficiency of your application. Health Center can save the data obtained from monitoring an application and load it again for analysis at a later date.

Starting with IBM Java 5 SR8 or IBM Java 6 SR1, The Health Center client can be installed within the IBM Support Assistant Workbench.

"Health Center provides visibility, monitoring and profiling in the following application areas:

• Performance
  
  
• Java method profiling: The Health Center uses a sampling method profiler to diagnose applications showing high CPU usage. It's low overhead which means there is no need to specify in advance which parts of the application to monitor, the Health Center simply monitors everything. It works without recompilation or byte code instrumentation and shows where the application is spending its time, by giving full call stack information for all sampled methods.
  
  
• Lock analysis: Synchronization can be a big performance bottleneck on multi-CPU systems. It is often difficult to identify a hot lock or assess the impact locking is having on your application. Health Center records all locking activity and identifies the objects with most contention. Health Center analyses this information, and uses it to provide guidance about whether synchronization is impacting performance
  
  
• Garbage collection: The performance of Garbage Collection (GC) affects the entire application. Tuning GC correctly can potentially deliver significant performance gains. Health Center identifies where garbage collection is causing performance problems and suggests more appropriate command line options.
  
  
• Memory usage
  The Health Center will identify if your application is using more memory than seems reasonable, or where memory leaks occur. It then suggests solutions to memory issues, as well as Java heap sizing guidance.
  
  
• System Environment
  Health Center uses an 'environment perspective' to provide details of the Java version, Java classpath, boot classpath, environment variables, and system properties. This is particularly useful for identifying problems on remote systems or systems where you do not control the configuration. If the Health Center detects misconfigured applications, it will provide recommendations on how to fix it.
  
  
• Java Class loading
  |Health Center provides class loading information, showing exactly when a class has been loaded and whether it is cached or not. This helps you determine whether your application is being affected by excessive class loading "


To Install Health Center:

Health Center is installed as a plug-in for IBM Support Assistant (ISA), therefore, ISA must be installed prior to obtaining the Java Health Center.

Step 1 – Prepare to install Health Center
1. Download and install the IBM Support Assistant Workbench.
2. Install the Heath Center in the ISA Workbench
   • Start the IBM Support Assistant Workbench.
   • If the "IBM Support Assistant Customization Wizard" is displayed. click Cancel to exit this wizard.
   • From the menu bar in ISA, select Update > Find New... > Tools Add-ons. The "Find new tools add-ons" wizard will be displayed.
   • Type health in the search box, then click the arrow next to JVM-based Tools to show matching tools.
   • Find for the Health Center add-on
     
     
     
     
   • Select "IBM Monitoring and Diagnostic Tools for Java - Health Center" from the list then click Next.
   • Complete the wizard by following the on-screen instructions.
   • IBM Support Assistant will prompt you to restart the Workbench - select Yes to restart.

Step 2 - Launch the Health Center client:
1. Start the IBM Support Assistant Workbench.
2. From the Welcome page, click Analyze Problem.
3. On the "Analyze Problem" tab, select Tools as below.
   
   Where to find the installed tools in the ISA Workbench
   
   
4. You will be presented with a list of all the installed tools. Select "IBM Monitoring and Diagnostic Tools for Java - Health Center" and then click on Launch.
5. The Health Center application will now launch and the Health Center: Connection wizard will be displayed.

Important note: Your application must be enabled for monitoring before Health Center can be connected.


Step 3 - Enable your application for monitoring:


1. On the first page of the Health Center: Connection wizard, click the 'Enabling an application for monitoring' link as below:
   
   Health Center Connection wizard application enablement link
   
   
2. Follow the help topic displayed:
   
   1. Installing the Health Center agent
      1. After clicking on "Install the Health Center Agent", you will find a list of agents to choose from. Choose the one that matches the Java version in which WebSphere is running:
         
         Windows x86 32-bit
         Windows x86 64-bit
         Linux® x86 32-bit
         Linux x86 64-bit
         Linux s390 31-bit
         Linux s390 64-bit
         Linux ppc 32-bit
         Linux ppc 64-bit
         AIX ppc 32-bit
         AIX ppc 64-bit
         z/OS 31-bit
         z/OS 64-bit
         
         Note: This might not be the same as the operating system you are running. For example, you might be running a 32-bit Java on a Windows® 64-bit system; in this case you should download the Windows 32-bit agent package.
         
      2. Install the agent.
         Installing on Microsoft Windows, AIX and Linux:
         
         You must download and extract the agent package into a specific directory of the JRE that you are using to start your application. This directory is the parent directory of the jre directory.
         
         For monitoring WebSphere, the jre directory is under WebSphere such as:
         C:\Program Files\IBM\WebSphere\AppServer61\java\jre
         
         For example, on Microsoft Windows, if your JRE is in the
         C:\Program Files\IBM\WebSphere\AppServer61\java\jre
         directory, extract the contents of the Windows x86 32-bit agent package into
         C:\Program Files\IBM\WebSphere\AppServer61\java
         
         When extracted, you see a healthcenter.jar file in the jre\lib\ext directory.
         Example: Your healthcenter.jar is in
         C:\Program Files\IBM\WebSphere\AppServer61\java\jre\lib\ext.
         
   2. Starting a Java application with the Health Center agent enabled
      To enable the Health Center for use with WebSphere Application Server:
      1. In the Administrative Console , select Application servers > *server_name* > Process Definition > Java Virtual Machine-> Generic JVM Arguments
      2. Enter the correct string for your Java™ Virtual Machine (JVM) version:
         
         On UNIX® system based platforms:
         
         For Java 5 SR9 and earlier or Java 6 SR4 and earlier, use:
         -agentlib:healthcenter -Xtrace:output=/tmp/perfmon.%p.out
         
         For Java 5 SR10 and later, or Java 6 SR5 and later, use:
         -Xhealthcenter
         
         On Microsoft Windows:
         
         For Java 5 SR9 and earlier or Java 6 SR4 and earlier, use:
         -agentlib:healthcenter -Xtrace:output=C:\temp\perfmon.%p.out
         
         For Java 5 SR10 and later, or Java 6 SR5 and later, use:
         -Xhealthcenter
         
      3. Apply the changes and save the settings at the top of the page.
      4. Restart the JVM.
         On UNIX system based platforms, the perfmon*.out files are in /tmp.
         On Microsoft Windows, the perfmon*.out files are in your temporary directory.
      5. Connect to the server from the Health Center client. The default port number is 1972.
         

Step 4 - Connect Health Center to the enabled Java application:

Complete the Health Center: Connection wizard to start monitoring the enabled Java application.

For further information refer to the help within ISA/Health Center.