Typically, when the top entry is represented by a single-digit percentage, you should not see application CPU performance issues unless the entry describes an obscure method that you did not expect to see.

Related Topics

•Java Method HotSpots (page 118)

•Process CPU Usage Alert (page 113)

•System CPU Usage Alert (page 114)

Viewing the Application Load

Use the Heap Monitor display.

This metric shows how busy the application is. It checks to see whether it is doing lots of allocations, which typically corresponds to the load level, or whether it is idle.

When you select a coarse granularity of the view (1 to 24 hours), and assuming that there is no memory leak, you will notice the overall change of behavior in heap size and garbage collection pattern. This setting can help you understand the correlation between the application load and the pressure on the heap.

If it seems a significant amount of time is spent in garbage collection, (gray in selected areas of the display), it means that the heap was not adequately sized — it was too small for the load on the application at that time. This behavior may also mean that the load was too high for the given hardware and software configuration.

Related Topics

•Heap Monitor (page 122)

•Percentage of Time Spent in Garbage Collection (page 125)

•Heap Usage Notification (page 111)

Checking for Long Garbage Collection Pauses

Use the Heap Monitor display and select the shortest time interval.

Most garbage collections take several seconds at most to execute. Very large heaps, however, may take up to several minutes.

Although the display does not show numerical values for the garbage collection duration, you can look for extra wide garbage collection bars, which correspond to garbage collection pauses. They will likely cause transient service-level objective (SLO) violations.

If intermittent, very long garbage collections are a potential problem in a given environment, you can select appropriate garbage collection algorithms with a JVM option. Refer to your JVM documentation.

Related Topics

•Heap Monitor (page 122)

•GC Duration (page 124) and GC Duration Notification (page 110)

•Garbage Collections (page 123)

•Heap Usage Notification (page 111)

•Data Collection with -Xverbosegc (page 80)

•Basic Garbage Collection Concepts (page 87)

Checking for Application Paging Problems

Use the Heap Monitor display, selecting a short time interval.

If multiple consecutive garbage collections take extraordinary time to run, this may indicate an excessive paging problem, called thrashing, where the physical memory available to the application is too small for the specified maximum size.

40 Monitoring Applications