Thanks for your work @loicmathieu!

I created a PR containing small minor improvements and the RSS tests ignored for Mac OS.

Feedbacks for improvement:

• A test fails if the RSS exceeds this given by @ExpectRSS annotation.
  So, @ExpectRSS could be renamed into @ExpectMaxRSS.

• Main issue
  A test annotated with a JVM annotation is launched in a specific JVM with the help of a ProcessBuilder (see NewJvmTestLauncher class). So the OS should create a specific process to run this test. Therefore, RSS would be measured without having to disable JVM forking in the following use cases mentioned by one of your code comment:

   * Some use case con take advantage of not forking to globally measure the RSS of the Test class,
     * taken into account the following part of the test execution:
     * - Global initilizer (static block, @BeforeAll or @BeforeClass annotated methods)
     * - Other extension that "starts an application" for integration testing (Spring or Quarkus test support)
     */
    boolean forkJvm() default true;

• Could you please fix a compilation warning if it is needed to can skip a JVM fork from an annotation parameter:

[WARNING] ... SetOfAnnotationConfigs.java uses unchecked or unsafe operations.

• Could you please create a PR for the documentation?
  To clone the doc repository: git clone https://github.com/quick-perf/doc.wiki.git
  A page gathers JVM annotations: https://github.com/quick-perf/doc/wiki/JVM-annotations

RSS annotations are very promising! Thanks!

@jeanbisutti I merged your PR thanks.

RSS tests ignored for Mac OS.

MacOS is a POSIX system so it should works. We can merged as is and open an issue for it if I didn't find why it didn't works. Do you have a Mac? If so you can have a look maybe the directory for the PID file is not the same on MacOS and Linux ...

• A test fails if the RSS exceeds this given by @ExpectRSS annotation.
  So, @ExpectRSS could be renamed into @ExpectMaxRSS.

Done

A test annotated with a JVM annotation is launched in a specific JVM with the help of a ProcessBuilder (see NewJvmTestLauncher class). So the OS should create a specific process to run this test. Therefore, RSS would be measured without having to disable JVM forking in the following use cases mentioned by one of your code comment [...]

I'm not happy with the fork/nofork dance and I need to check some usecases before deciding what to do with it. Maybe what we need is a way to define from wich PID we gather the statistics (default to the current one) as some framework could decide to start the process before (like Quarkus did for native tests). That's why it's still a draft PR :). I will take your feedback into account and analyse some usecase before going back with a better implementation.

Could you please create a PR for the documentation?

Yes, and I also need to make the documentation for the JUnit5 support :)

MacOS is a POSIX system so it should works. We can merged as is and open an issue for it if I didn't find why it didn't works. Do you have a Mac? If so you can have a look maybe the directory for the PID file is not the same on MacOS and Linux ...

I don't have a Mac... We could open an issue for this.

It seems a good idea to explore several use cases before choosing the final implementation.

Maybe what we need is a way to define from wich PID we gather the statistics (default to the current one)

I think the correct implementation for gathering the PID is default to the current one or the forked one in case of JVM forks. The RSS annotation should not mandate a fork by itself. Or should it ?

JVM annotation is launched in a specific JVM with the help of a ProcessBuilder (see NewJvmTestLauncher class). So the OS should create a specific process to run this test.

Therefore, I see several advantages of forking the JVM with the RSS annotations:

• The stopRecording method of ProcessStatusRecorder could retrieve the current PID, after retrieve the RSS related to this PID and after save it in disk. The findRecord method of ProcessStatusRecorder would retrieve RSS value from disk. The implementation is rather simple.
• Several tests measuring RSS and excuting concurrently would be independant

Several tests measuring RSS and excuting concurrently would be independant

Wether or not they measure RSS, several test executing concurrently or the one after the other could impact RSS significantly so yes, forking is needed ...

Anyway I want to test this with SringBoot/Micronaut/Quarkus integration tests as this annotation will make sense to measure RSS of an integration test not much of a simple unit test

Thanks for your work @loicmathieu! It's great!

@jeanbisutti I remove the ability to avoid forking the VM as discussed.
This PR is ready now :)

Ah, just saw that it's already merged ;)