How to get on-the-fly instrumentation with JaCoCo on a running java app

Asked May 22 '19 at 12:20

Active May 23 '19 at 08:32

Viewed 57 times

I am trying to identify which classes and, if possible methods, are used by a running java app.

In the JaCoCo Coverage Analysis Diagram at https://www.eclemma.org/jacoco/trunk/doc/implementation.html they mention the On-the-fly instrumentation available via their Java Agent.

I am fairly new to java and I was able to add the maven plugin to the project but I am confused as to what I am supposed to do now. I assume I somehow need to run this and pass the process id of the running app and then use the "file system" or "tcp" options to retrieve the used classes/methods captured.

Any details/explanations will be highly appreciated.

edited May 23 '19 at 08:32

Mark Rotteveel

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asked May 22 '19 at 12:20

Cristian G

It sounds like you don't even necessarily need on-the-fly instrumentation. Why do you think that you do? – Michael May 22 '19 at 12:35
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Do you want to get coverage of the normal execution of your program? From what I understand maven plugin only calculates coverage of test executions. – Gonzalo Matheu May 22 '19 at 12:36
@Michael I need it for applications that are in production, are there any other options? – Cristian G May 22 '19 at 12:50
@GonzaloMatheu from what I could understand using the plugin only abstracts some of the settings, I did not know it works only for test executions. What should I use for on-the-fly code coverage? – Cristian G May 22 '19 at 12:52
@CristianG You shouldn't run coverage against production code. – Michael May 22 '19 at 12:54
@Michael my bad, we have some scenarios and we want to run coverage against them, not in production. – Cristian G May 22 '19 at 12:55
How do you execute the application? Maven? with Java? – Gonzalo Matheu May 22 '19 at 12:56
@GonzaloMatheu as far as I know is Maven, but I might be mistaken. Does it make a difference? – Cristian G May 22 '19 at 12:58
The way to activate the Jacoco agent will vary depending on how you execute your program. – Gonzalo Matheu May 22 '19 at 13:09
@GonzaloMatheu how would I do it for Maven? Can I configure it somehow or pass some arguments? I would also prefer the tcp version. – Cristian G May 22 '19 at 13:12

How to get on-the-fly instrumentation with JaCoCo on a running java app

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