What is the number of parallel threads managed by the internal mechanism of ForkJoinPool?

The internal mechanism of ForkJoinPool in Java manages the number of threads equal to the number of available processor cores (CPU), which can be obtained through Runtime.getRuntime().availableProcessors().

By default, the pool size is set to the number of processors to efficiently utilize system resources without excessive context switching.

Example of obtaining the number of threads in ForkJoinPool:

int parallelism = Runtime.getRuntime().availableProcessors();
ForkJoinPool pool = new ForkJoinPool(parallelism);
System.out.println("Number of threads in ForkJoinPool: " + parallelism);