HPjmeter 4.3 User's Guide

due to the stress on the JVM, such phenomena are typically much more costly than just running

this method exclusively in interpreted mode.

Repeated compilation problems may result in SLO violations and will affect some or all transactions.

Read the JVM Release Notes to learn how to disable compilation of selected methods for the HP

Java HotSpot Virtual Machine.

Related Topics

• Excessive Compilation Alert (page 128)

• Method Compilation Count (page 156)

• Method Compilation Frequency (page 157)

Identifying Too Many Classes Loaded

Use the Loaded Classes display.

This display can be used to determine if the pool of classes loaded into memory stabilizes over

time to a constant value, which is normal.

In some JVMs, like HotSpot, loaded classes are located in a dedicated memory area, called the

Permanent Generation, which is typically much smaller that the whole heap. If the application

repeatedly loads new classes, either from external sources, or by generating them on the fly, this

area overfills and the application abnormally terminates. This will correspond with the value of

this metric constantly growing up to the point of failure.

If you find that the application terminates because the number of loaded classes is too large for

the area of memory dedicated to this purpose, you can increase the heap area for the class storage

by using a JVM option. However, if changing the dedicated memory size will not help the situation

because the number of the loaded classes is unconstrained, this is an application design issue that

needs to be solved.

NOTE: An overflow of the area dedicated to class storage can cause the application to terminate,

sometimes with an OutOfMemoryError message, even if there is plenty of space available on

the heap. Consult your JVM documentation on how to increase the area dedicated for class storage,

if necessary.