Remote Runtime Instrumentation

Question

I am new at instrumentation world. I am trying to instrumentate a remote JVM at Runtime. Actually, i have to log all classes or part of them and transform them.. I have read many documents and i found this code HERE

I changed the code and i replaced

// Run sayHello in a loop
Person person = new Person();
for(int i = 0; i < 1000; i++) {
    person.sayHello(i);
    person.sayHello("" + (i*-1));
    Thread.currentThread().join(5000);
}

by this one:

for (int i = 1; i < args.length; i++) {
    String className = args[i] ;
    System.out.println("className" + className);
    // Call transformClass on the transformer MBean
    server.invoke(on, "transformClass", new Object[]{className}, new String[]{String.class.getName()});
}

But i found that args.length=0 I don't know what the args[] contain...And if it contains loaded classes (i assume) then why it is empty..

Any help please?

score 0 · Accepted Answer · edited May 23 '17 at 11:50

0

I wrote that code, but I don't understand what you're trying to do in your code. The referenced github gists were in reference to the answer to this SO question, so it may help you to re-read that question.

There are multiple steps involved, and the classes need to be packaged in a specific way, but the basics are:

Use the AgentInstaller to install the instrumentation agent into a running JVM.
Connect to the JVM via JMX.
Invoke the transformClass(String className, String methodName, String methodSignature) MBean operation to instrument the class using the demo transformer.

edited May 23 '17 at 11:50

Community

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answered Apr 07 '16 at 16:46

Nicholas

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thnx @Nicholas... it's done ;) But i want to ask you an other question: with your code on github, could I instrument classes witch are locatedin another application? – GEmyy Apr 07 '16 at 17:24
@GEmyy; Yup. That's the idea. Install the agent into the target app, then instrument it. – Nicholas Apr 07 '16 at 18:21
thnx @Nicholas, but how should i install the agent into the target app? the "AgentInstaller" Class exists in my program But i want to instrumentate another application.. Should I just change the PID in the AgentInstaller Class or what exactely? – GEmyy Apr 08 '16 at 08:07
Because when i do this: VirtualMachine vm = VirtualMachine.attach(pid_of_the _other_app); I got 2 crashed apps – GEmyy Apr 08 '16 at 08:30

Remote Runtime Instrumentation

1 Answers1