A DESCRIPTION OF THE PROBLEM :
Process exposes FileInputStream and FileOutputStream for over operating system pipes connected to subprocesses. FileInputStream and FileOutputStream block native threads that enter them. Thus, if virtual threads are used to interact with Process I/O streams, all the carrier threads in the virtual thread pool may be tied up.

There used to be ForkJoinPool "compensation" enabled for FileInputStream and FileOutputStream but that was removed in JDK-8329593, causing a regression.

REGRESSION : Last worked in version 21.0.8