The Status Summary page lists the various subsystems profiled by the Health Center which include Classes, Environment, Garbage Collection, I/O data, Locking, Native Memory and Method Profiling. This page provides a summary of the “health” of the various subsystems. The summary will indicate if there are any potential problems with the particular subsystem (indicated in Red color), or tuning suggestions for optimizing the subsystem further (indicated in Amber) and an indication of a healthy subsystem (with no problems) denoted in Green color.
Health Center provides class loading information, showing exactly when a class has been loaded into the Java Virtual Machine (JVM) and whether the class is cached or not (in the Shared Classes Cache). This helps users in determining whether their application is being affected by excessive class loading.
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 are not able to access the configuration details. If the Health Center detects mis-configured applications, it will provide recommendations on how to fix it. For example a debug trace option introduced during development cycle may have been left as is with possible performance implications when moved to production. Environment Subsystem will point to such a scenario.
Garbage Collection Subsystem:
Garbage Collection is the most significant performance bottleneck for Java applications. 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.
Health Center uses an 'I/O perspective' to monitor application input or output (I/O) tasks as they run. Users can use this perspective to monitor how many and which files are open, and to help solve problems such as when the application fails to close files.
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.
Native Memory Subsystem:
"Native memory" subsystem gives a view of 'Process Virtual Memory' and 'Process Physical Memory' plotted against time with JVM start time as the reference.
The Health Center uses a sampling method profiler to diagnose applications showing high CPU usage giving full call stack information for all sample methods. Health Center works without recompilation or bytecode instrumentation and shows where the application is spending its time.