StreamOpFlag.* and OutOfMemoryError when going parall

[Christian Mallwitz]

Hi,

Using lambda-8-b67-linux-i586-03_dec_2012 I'm trying to compute n (not
necessarily the first n) prime numbers:

import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class LambdaExample3 {

    public static boolean isPrime(long n) {
        if (n <= 1) { return false; }
        if (n == 2) { return true; }
        for (int i = 2; i <= Math.sqrt(n) + 1; i++) { if (n % i == 0)
return false; }
        return true;
    }

    public static void main(String[] args) {

        Stream<Long> stream =
Streams.parallel(Streams.spliteratorUnknownSize(new Iterator<Long>() {
                private long n = 0;
                @Override public boolean hasNext() { return true; }
                @Override public Long next() { return ++n; }
                }),
            // fails with OutOfMemoryError
            // StreamOpFlag.toStreamFlags(StreamOpFlag.NOT_SIZED,
StreamOpFlag.INITIAL_OPS_VALUE)
            // fails with OutOfMemoryError
            // StreamOpFlag.NOT_SIZED
            // works, but no speed-up to non-parallel version
            StreamOpFlag.INITIAL_OPS_VALUE
            );

        stream
            .filter(LambdaExample3::isPrime)
            .limit(300000)
            .forEach(l -> { /*System.out.println(l);*/ });
    }
}

I'm struggling with the StreamOpFlag parameter. What should I pick?
INITIAL_OPS_VALUE seems to work but isn't running anything in parallel
(at least it is not faster than the serial version). NOT_SIZED isn't
working but failing miserably with an  OutOfMemoryError. IS_PARALLEL
is not needed because I already use parallel() - should specifying
IS_PARALLEL and using Streams.stream() supposed to go parallel as
well?

Is the OutOfMemoryError caused by a bug? The OutOfMemoryError is
reported from a fork/join pool thread so at least it is going
parallel? Am I missing something?

Thanks
Christian