Custom thread pool in Java 8 parallel stream

Question

Is it possible to specify a custom thread pool for Java 8 parallel stream? I can not find it anywhere.

Imagine that I have a server application and I would like to

Answer 1

you can try implementing this ForkJoinWorkerThreadFactory and inject it to Fork-Join class.

public ForkJoinPool(int parallelism,
                        ForkJoinWorkerThreadFactory factory,
                        UncaughtExceptionHandler handler,
                        boolean asyncMode) {
        this(checkParallelism(parallelism),
             checkFactory(factory),
             handler,
             asyncMode ? FIFO_QUEUE : LIFO_QUEUE,
             "ForkJoinPool-" + nextPoolId() + "-worker-");
        checkPermission();
    }

you can use this constructor of Fork-Join pool to do this.

notes:-- 1. if you use this, take into consideration that based on your implementation of new threads, scheduling from JVM will be affected, which generally schedules fork-join threads to different cores(treated as a computational thread). 2. task scheduling by fork-join to threads won't get affected. 3. Haven't really figured out how parallel stream is picking threads from fork-join(couldn't find proper documentation on it), so try using a different threadNaming factory so as to make sure, if threads in parallel stream are being picked from customThreadFactory that you provide. 4. commonThreadPool won't use this customThreadFactory.