Question Regarding JEP 444: Virtual Threads and Use of ForkJoinPool

[Alan Bateman]

On 14/06/2023 13:33, Olivier Peyrusse wrote:
> And following on this question regarding FJP, is there any possible interaction between the virtual threads and any library externally using ForkJoinPools?
>
> I am asking this question with this JUnit issue in mind https://github.com/junit-team/junit5/issues/3108
> For example, if a test were to be executed by JUnit executor relying on the FJP, and if the test were using Virtual Threads, would we see interactions between those Virtual threads and JUnit executor, particularly through the test `thread instanceof ForkJoinWorkerThread`?
>
> I am trying to build an example to see how the two will interact and see with my own eyes.
>

Thread.currentThread() will return the Thread object for the virtual 
thread, it won't return the underlying ForkJoinWorkerThread used as the 
carrier.

I'm not sure how to read the referenced issue. Does JUnit's parallel 
executor create its own ForkJoinPool to run tests or does it use the 
common pool? In any case, it will be a separate pool to that used for 
virtual threads.

-Alan