Monitoring & Diagnose WebSphere Application Server

IBM have a very low overhead monitoring tool solution to do the task. It is Java Health Center or known as HC.

"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."

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

·         Performance

v  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.

v  Lock analysis: Synchonization 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

v  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.

Video: Overview of Health Center

Installing HC

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.

·         first download and install ISA (IBM support assistant)

·         in the ISA menu, Update > Find New… > Tools Add-ons ->Find new tools add-ons

·         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. ISA will prompt you to restart the Workbench – select Yes to restart.

·         Now, start the ISA

·         go to Analyze Problem and select Tools ->IBM Monitoring and Diagnostic Tools for Java – Health Center –>launch

Your application must be enabled for monitoring before Health Center can be connected.  You must install the Health Center Agent.

Installing Agent

·         In the health center tool, on the first screen –> click Enabling an application for monitoring. This will show you the help on how to setup the agents.

·         Now click on Install the Health Center Agent. It shows you the list of available agents. Choose the appropriate agent to suite your application server environment.

·         You must download and extract the agent package into a specific directory of the JRE that you are using to start your application.

·         For monitoring WebSphere, the jre directory is under WebSphere:

Websphere_Install_Root/java/jre

·         When extracted, you see a healthcenter.jar file in the jre\lib\ext directory

Connecting HC and websphere

To enable the Health Center for use with WebSphere Application Server:

·         In the Administrative Console , select Application servers> server_name > Process

Definition > Java Virtual Machine-> Generic JVM Arguments

For Java 5 SR9 and earlier or Java 6 SR4 and earlier, add: 

-agentlib:healthcenter -Xtrace:output=/tmp/perfmon.%p.out 

For Java 5 SR10 and later, or Java 6 SR5 and later, add: 

-Xhealthcenter

·         Apply changes, save and restart JVM

·         Connect to the server from the Health Center client. The default port number is 1972.

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