Is it possible to register if a class is used in the JVM?

Question

I have Tomcat running applications. I cannot restart Tomcat, but I would like to monitor the use of class files.

I would like to register if the specified class is used. Is it possible? How could I do this?

Using a class. If an object for this class is created or methods are called, etc.

Clarification: I cannot restart the application. Each solution with recompilation of working code is unacceptable. This makes the problem harder.

Remote debugging / JMX is not yet enabled. It will be a similar effort, for example, recompiling the application to activate it.

Platform - RHEL, 64 bit.

Answer 1

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Answer 2

, . , . fav - System.out.println:)

Answer 3

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Answer 4

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ClassLoader#findLoadedClass()

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Answer 5

Solaris OS X, DTrace-.

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Answer 6

class X {
 static {
  System.out.println("class X has been loaded");
 }
 ...
}

.

If you cannot edit the code and you have JRE 6, you can try the jmap tool

jmap -histo <pid>

it will display a histogram of your heap, including all loaded classes.

Using jps, you can find out pid

Answer 7

With the JRockit JVM, you can run your application with -Xverbose: class = info to get information about loading classes.